Apparatus and method for transmitting/receiving activation indicator regarding component carrier in wireless communication system

ABSTRACT

A method for supporting activation/deactivation of serving cells by a base station (BS) in a wireless communication system provides decreased overhead and decreased power consumption for a user equipment (UE). The method includes configuring M supportable serving cells in the UE, configuring an indicator indicating activation/deactivation of each of the M serving cells, configuring a medium access control (MAC) message which includes a MAC control element (CE) and a logical channel identifier (LCID), the MAC CE including the indicator configured for each of the M serving cells and having a length corresponding to an integer multiple of 8 bits, the LCID indicating that the MAC CE includes the indicator indicating activation/deactivation of each serving cell, and transmitting the configured MAC message to the UE. Accordingly, a control channel or data channel regarding a component carrier is selectively received depending on whether the component carrier is activated.

This application is a continuation of U.S. application Ser. No.13/875,808, filed on May 2, 2013, which is a divisional of U.S. patentapplication Ser. No. 12/916,203, filed on Oct. 29, 2010, now issued asU.S. Pat. No. 8,538,411, and claims priority from and the benefit under35 U.S.C. §119(a) of Korean Patent Application No. 10-2009-0104586,filed on Oct. 30, 2009, and Korean Patent Application No.10-2010-0088151, filed on Sep. 8, 2010, the disclosures of which areincorporated herein by reference for all purposes.

BACKGROUND

1. Field

The following description relates to wireless communications, and moreparticularly, to an apparatus and method for constructing an activationgroup regarding a component carrier in a wireless communication systemhaving a plurality of component carriers and for transmitting andreceiving activation information generated on the basis of theconstructed activation group.

2. Discussion of the Background

Next generation wireless communication systems support a high data rate.For this, various techniques, such as multiple input multiple output(MIMO), cooperative multiple point transmission (CoMP), relay, etc.,have been researched, but another solution may be to increase abandwidth.

However, currently, a frequency resource is in a saturation state, andvarious schemes are partially used in a wide frequency band. For thisreason, in order to ensure a broadband bandwidth in order to satisfy ahigher data rate, a system is designed to satisfy a basic requirementwhich requires separate bands capable of operating respectiveindependent systems, and a carrier aggregation (CA) is introduced. Inconcept, the CA aggregates a plurality of bands into one system. In thiscase, a band that can be independently managed is defined as a componentcarrier (CC).

SUMMARY

Exemplary embodiments of the present invention provide a systemincluding a plurality of component carriers satisfying a servicerequirement in a next generation wireless communication system, and amethod for the system.

Exemplary embodiments of the present invention provide an apparatus andmethod for configuring an activation group in correspondence withspecific information in a wireless communication system using aplurality of component carriers.

Exemplary embodiments of the present invention provide an apparatus andmethod for generating an activation indicator on the basis of anactivation group configured in correspondence with specific informationin a wireless communication system using a plurality of componentcarriers.

Exemplary embodiments of the present invention provide an apparatus andmethod for indicating activation and deactivation of a component carrierconfigured in correspondence with specific information in a wirelesscommunication system using a plurality of component carriers.

Exemplary embodiments of the present invention provide an apparatus andmethod for transmitting and receiving an activation indicator indicatingactivation of a selected component carrier in a wireless communicationsystem using a plurality of component carriers.

Exemplary embodiments of the present invention provide an apparatus andmethod for transmitting and receiving an activation indicator indicatingdeactivation of a selected component carrier in a wireless communicationsystem using a plurality of component carriers.

Exemplary embodiments of the present invention provide an apparatus andmethod for transmitting and receiving an activation indicator indicatingactivation or deactivation of a selected component carrier byconstructing the indicator in a format of a bitmap having apredetermined size in a wireless communication system using a pluralityof component carriers.

Exemplary embodiments of the present invention provide an apparatus andmethod for transmitting and receiving an activation indicator indicatingactivation or deactivation of a secondary serving cell (SSC), to which asystem information block type 2 (SIB2) connection is established, byconstructing the indicator to have the same length as informationindicating a component carrier index in a wireless communication system.

Exemplary embodiments of the present invention provide an apparatus andmethod for transmitting and receiving an activation indicator indicatingactivation or deactivation of an SSC, to which an SIB2 connection isestablished, by using medium access control (MAC) signaling in awireless communication system.

Additional features of the invention will be set forth in thedescription which follows, and in part will be apparent from thedescription, or may be learned by practice of the invention.

An exemplary embodiment provides a method for supportingactivation/deactivation of serving cells by a base station (eNB) in awireless communication system, the method including configuring Msupportable serving cells in a user equipment (UE), configuring anindicator indicating activation/deactivation of each of the M servingcells, configuring a medium access control (MAC) message which includesa MAC control element (CE) and a logical channel identifier (LCID), theMAC CE including the indicator configured for each of the M servingcells and having a length corresponding to an integer multiple of 8bits, the LCID indicating that the MAC CE includes the indicatorindicating activation/deactivation of each serving cell, andtransmitting the configured MAC message to the UE.

An exemplary embodiment provides a method for supportingactivation/deactivation of serving cells by a user equipment (UE) in awireless communication system, the method including receiving a mediumaccess control (MAC) message from a base station (eNB), confirming by alogical channel identifier (LCID) that an indicator is included in thereceived MAC message, and confirming that the indicator indicatesactivation/deactivation of each of M serving cells configured in the UEby using a MAC control element (MAC CE) having a length corresponding toan integer multiple of 8 bits, and receiving a downlink control channelor a downlink data channel from the eNB or transmitting an uplink datachannel to the eNB by using an activated serving cell based on theconfirmed indicator.

An exemplary embodiment provides a base station (eNB) to supportactivation/deactivation of serving cells in a wireless communicationsystem, the eNB including an activation group configuration unit toconfigure M supportable serving cells in a user equipment (UE), anactivation indicator generation unit to generate an indicator indicatingactivation/deactivation of each of the M serving cells, a messagetransmission unit to configure a medium access control (MAC) message andto transmit the configured MAC message to the UE, the MAC messageincluding a MAC control element (MAC CE) and a logical channelidentifier (LCID), the MAC CE including the indicator configured foreach of the M serving cells and having a length corresponding to aninteger multiple of 8 bits, the LCID indicating that the MAC CE includesthe indicator.

An exemplary embodiment provides a user equipment (UE) to supportactivation/deactivation of serving cells in a wireless communicationsystem, the user equipment including a reception processing unit toreceive a medium access control (MAC) message, an activation groupconfirmation unit to confirm by logical channel identifier (LCID) thatan indicator is included in the received MAC message, and to confirmthat the indicator indicates activation/deactivation of each of Mserving cells configured in the UE by using a MAC control element (CE)having a length corresponding to an integer multiple of 8 bits, and aninformation analysis unit to receive a downlink control channel or adownlink data channel, or to transmit an uplink data channel, by usingan activated serving cell based on the confirmed indicator.

An exemplary embodiment provides a method for supportingactivation/deactivation of component carriers by a base station (eNB) ina wireless communication system supporting multi component carriers, themethod including configuring M supportable component carrier(CC)s in auser equipment (UE), configuring an indicator indicatingactivation/deactivation of each of the M CCs, configuring a mediumaccess control (MAC) message which includes a MAC control element (CE)and a logical channel identifier (LCID), the MAC CE including theindicator configured for each of the M CCs and having a lengthcorresponding to an integer multiple of 8 bits, the LCID indicating thatthe MAC CE includes the indicator indicating activation/deactivation ofeach CC, and transmitting the configured MAC message to the UE. The CCis a cell to transmit and receive information between the eNB and theUE, that the cell has a linkage between uplink CC and downlink CC.

An exemplary embodiment provides a method for supportingactivation/deactivation of component carriers by a user equipment (UE)in a wireless communication system supporting multi component carriers,the method including receiving a medium access control (MAC) messagefrom a base station (eNB), confirming by a logical channel identifier(LCID) that an indicator is included in the received MAC message, andconfirming that the indicator indicates activation/deactivation of eachof M component carrier(CC)s configured in the UE by using a MAC controlelement (MAC CE) having a length corresponding to an integer multiple of8 bits, and receiving a downlink control channel or a downlink datachannel from the eNB or transmitting an uplink data channel to the eNBby using an activated CC based on the confirmed indicator. The CC is acell to transmit and receive information between the eNB and the UE,that the cell has a linkage between uplink CC and downlink CC.

An exemplary embodiment provides a base station (eNB) to supportactivation/deactivation of component carrier(CC)s in a wirelesscommunication system, the eNB including an activation groupconfiguration unit to configure M supportable component carrier(CC)s ina user equipment (UE), an activation indicator generation unit togenerate an indicator indicating activation/deactivation of each of theM component carrier(CC)s, a message transmission unit to configure amedium access control (MAC) message and to transmit the configured MACmessage to the UE, the MAC message including a MAC control element (MACCE) and a logical channel identifier (LCID), the MAC CE including theindicator configured for each of the M component carrier(CC)s and havinga length corresponding to an integer multiple of 8 bits, the LCIDindicating that the MAC CE includes the indicator. The CC is a cell totransmit and receive information between the eNB and the UE, that thecell has a linkage between uplink CC and downlink CC.

An exemplary embodiment provides a user equipment (UE) to supportactivation/deactivation of component carrier(CC)s in a wirelesscommunication system, the user equipment including a receptionprocessing unit to receive a medium access control (MAC) message, anactivation group confirmation unit to confirm by logical channelidentifier (LCID) that an indicator is included in the received MACmessage, and to confirm that the indicator indicatesactivation/deactivation of each of M component carrier(CC)s configuredin the UE by using a MAC control element (CE) having a lengthcorresponding to an integer multiple of 8 bits, and an informationanalysis unit to receive a downlink control channel or a downlink datachannel, or to transmit an uplink data channel, by using an activatedcomponent carrier(CC) based on the confirmed indicator. The CC is a cellto transmit and receive information between the eNB and the UE, that thecell has a linkage between uplink CC and downlink CC.

An exemplary embodiment provides a method for supportingactivation/deactivation of component carrier(CC)s by a base station(eNB) in a wireless communication system using a plurality of CCs havingfrequency bands that can be independently managed, the method includingdetermining, for each of the CCs, activation to instruct monitoring forreceiving a control channel and a data channel or at least one of thecontrol channel and the data channel or deactivation to instruct a stopof the monitoring for receiving the control channel and the datachannel, setting the determined activation or deactivation to a 1-bitindicator, wherein the activation is set to 1 and the deactivation isset to 0, and transmitting medium access control (MAC) signaling whichincludes the indicator for each of the CCs in a bit-stream having apredetermined length, to a user equipment (UE).

An exemplary embodiment provides a method for supportingactivation/deactivation of component carrier(CC)s by a user equipment(UE) in a wireless communication system using a plurality of CCs havingfrequency bands that can be independently managed, the method includingreceiving medium access control (MAC) signaling which includes anindicator configured for each of the CCs in a bit-stream having apredetermined length, confirming the indicator set for each of the CCsin the bit-stream having the predetermined length, activating acorresponding CC if the confirmed indicator is 1 or deactivating thecorresponding CC if the confirmed indicator is 0, and receiving acontrol channel and a data channel or at least one of the controlchannel and the data channel by monitoring the activated CC or notreceiving the control channel and the data channel by stoppingmonitoring of the deactivated CC.

An exemplary embodiment provides a base station (eNB) for supportingactivation/deactivation of component carrier(CC)s in a wirelesscommunication system using a plurality of CCs having frequency bandsthat can be independently managed, the eNB including a controller todetermine, for each of the CCs, activation to instruct monitoring forreceiving a control channel and a data channel or at least one of thecontrol channel and the data channel or deactivation to instruct a stopof the monitoring for receiving the control channel and the datachannel, and to set the determined activation or deactivation to a 1-bitindicator, wherein the activation is set to 1 and the deactivation isset to 0, and a transceiver medium access control (MAC) signaling whichincludes the indicator for each of the CCs in a bit-stream having apredetermined length, to a user equipment (UE).

An exemplary embodiment provides a user equipment (UE) for supportingactivation/deactivation of component carrier(CC)s in a wirelesscommunication system using a plurality of CCs having frequency bandsthat can be independently managed, the UE including a receptionprocessing unit to receive medium access control (MAC) signaling whichincludes an indicator configured for each of the CCs in a bit-streamhaving a predetermined length, an activation group confirmation unit toconfirm the indicator set for each of the CCs in the bit-stream havingthe predetermined length, and to activate a corresponding CC if theconfirmed indicator is 1 or deactivate the corresponding CC if theconfirmed indicator is 0, and an information analysis unit to receive acontrol channel and a data channel or at least one of the controlchannel and the data channel by monitoring the activated CC or not toreceive the control channel and the data channel by stopping monitoringof the deactivated CC.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the invention as claimed.Other features and aspects will be apparent from the following detaileddescription, the drawings, and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention, andtogether with the description serve to explain the principles of theinvention.

FIG. 1 shows a wireless communication system according to an exemplaryembodiment of the present invention.

FIG. 2 shows a case of simultaneously using 5 CCs having a frequencyband of 20 MHz or lower in a wireless communication system according toan exemplary embodiment of the present invention.

FIG. 3 shows a downlink control information activation group accordingto an exemplary embodiment of the present invention.

FIG. 4 shows a case where a missing region is generated when data isreceived using the control information activation indicator of FIG. 3.

FIG. 5 shows a control information activation group and a datainformation activation group in downlink according to an exemplaryembodiment of the present invention.

FIG. 6 is a flowchart for configuring a control information activationgroup according to an exemplary embodiment of the present invention.

FIG. 7 shows a structure of an activation group for each layer accordingto an exemplary embodiment of the present invention.

FIG. 8 is a flowchart for configuring a data information activationgroup according to an exemplary embodiment of the present invention.

FIG. 9 shows an example of transmitting an activation indicatorindividually for each CC of an activation group according to anexemplary embodiment of the present invention.

FIG. 10 is a flowchart for transmitting an activation indicator in aneNB according to an exemplary embodiment of the present invention.

FIG. 11 is a schematic view of a transmitter for transmitting anactivation indicator according to an exemplary embodiment of the presentinvention.

FIG. 12 shows a signal generation structure of a downlink physicalchannel for transmitting an activation indicator according to anexemplary embodiment of the present invention.

FIG. 13 is a flowchart for receiving an activation indicator accordingto an exemplary embodiment of the present invention.

FIG. 14 shows a receiver for receiving an activation indicator accordingto an exemplary embodiment of the present invention.

FIG. 15 is a diagram for explaining the concept of a primary servingcell (PSC) and a secondary serving cell (SSC).

FIG. 16 shows a MAC protocol data unit (PDU) including an activationindicator according to an exemplary embodiment of the present invention.

FIG. 17 shows a MAC control element including an activation indicatoraccording to an exemplary embodiment of the present invention.

FIG. 18 shows a MAC control element including an activation indicatoraccording to an exemplary embodiment of the present invention.

FIG. 19 shows a MAC control element including an activation indicatoraccording to an exemplary embodiment of the present invention.

FIG. 20 shows a MAC control element including an activation indicatoraccording to an exemplary embodiment of the present invention.

FIG. 21 shows a MAC control element including an activation indicatoraccording to an exemplary embodiment of the present invention.

FIG. 22 shows a MAC control element including an activation indicatoraccording to an exemplary embodiment of the present invention.

FIG. 23 shows a MAC control element including an activation indicatoraccording to an exemplary embodiment of the present invention.

FIG. 24 shows a MAC control element including an activation indicatoraccording to an exemplary embodiment of the present invention.

FIG. 25 shows a MAC control element including an activation indicatoraccording to an exemplary embodiment of the present invention.

FIG. 26 shows a MAC control element including an activation indicatoraccording to an exemplary embodiment of the present invention.

FIG. 27 shows a MAC control element including an activation indicatoraccording to an exemplary embodiment of the present invention.

FIG. 28 shows a MAC control element including an activation indicatoraccording to an exemplary embodiment of the present invention.

FIG. 29 shows a MAC control element including an activation indicatoraccording to an exemplary embodiment of the present invention.

FIG. 30 shows a MAC control element including an activation indicatoraccording to an exemplary embodiment of the present invention.

FIG. 31 shows a MAC control element including an activation indicatoraccording is to an exemplary embodiment of the present invention.

FIG. 32 shows a MAC control element including an activation indicatoraccording to an exemplary embodiment of the present invention.

FIG. 33 shows a MAC control element including an activation indicatoraccording to an exemplary embodiment of the present invention.

FIG. 34 shows a MAC control element including an activation indicatoraccording to an exemplary embodiment of the present invention.

FIG. 35 is a flowchart showing a method for transmitting an activationindicator according to an exemplary embodiment of the present invention.

Throughout the drawings and the detailed description, unless otherwisedescribed, the same drawing reference numerals are understood to referto the same elements, features, and structures. The relative size anddepiction of these elements may be exaggerated for clarity,illustration, and convenience.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

The invention is described more fully hereinafter with reference to theaccompanying drawings, in which exemplary embodiments of the inventionare shown. This invention may, however, be embodied in many differentforms and should not be construed as limited to the embodiments setforth herein. Rather, these exemplary embodiments are provided so thatthis disclosure is thorough, and will fully convey the scope of theinvention to those skilled in the art. In the drawings, the size andrelative sizes of layers and regions may be exaggerated for clarity.Like reference numerals in the drawings denote like elements.

FIG. 1 shows a wireless communication system according to an exemplaryembodiment of the present invention is applied. The wirelesscommunication system can be widely deployed to provide a variety ofcommunication services, such as voices, packet data, etc. Referring toFIG. 1, the wireless communication system includes a user equipment (UE)10 and an evolved Node B (eNB) 20. The UE 10 and the eNB 20 use variouspower allocation mechanisms described below.

The UE 10 collectively represents all user terminals used in wirelesscommunication and shall be construed as including not only a userequipment (UE) used in Wideband Code Division Multiple Access (WCDMA),Long Term Evolution (LTE), High Speed Packet Access (HSPA), etc., butalso a mobile station (MS), a user terminal (UT), a subscriber station(SS), a wireless device, etc., used in Global System for MobileCommunication (GSM).

The eNB 20 may be a cell and generally refers to a fixed station thatcommunicates with the UE 10 and may be referred to as anotherterminology, such as a base station (BS), a node-B, a base transceiversystem (BTS), an access point (AP), a relay, femto BS, etc.

That is, the eNB 20 collectively represents some frequency regionscovered by an eNB in Code Division Multiple Access (CDMA), a NodeB inWCDMA, etc., and shall be construed as including all various coverageareas, such as a mega cell, a macro cell, a micro cell, a pico cell, afemto cell, etc.

The UE 10 and the eNB 20 are transmitting and receiving entities used toimplement technical features or technical ideas described herein, andare not constrained by a specific term or name.

There is no restriction on a multiple access scheme used in the wirelesscommunication system. Various multiple access schemes can be used, suchas CDMA, time division multiple access (TDMA), frequency divisionmultiple access (FDMA), orthogonal frequency division multiple access(OFDMA), OFDM-FDMA, OFDM-TDMA, and OFDM-CDMA.

Hereinafter, a downlink represents communication from the eNB 20 to theUE 10, and an uplink represents communication from the UE 10 to the eNB20. In this case, in the downlink, a transmitter may be a part of theeNB 20, and a receiver may be a part of the UE 10. Further, in theuplink, the transmitter may be a part of the UE 10, and the receiver maybe a part of the eNB 20. In some cases, the downlink may representcommunication from the UE 10 to the eNB 20, and the uplink may representcommunication from the eNB 20 to the UE 10. In this case, in thedownlink, the transmitter may be a part of the UE 10, and the receivermay be a part of the eNB 20. Further, in the uplink, the transmitter maybe a part of the eNB 20, and the receiver may be a part of the UE 10.The downlink may also be referred to as a forward link, and the uplinkmay also be referred to as a reverse link.

Uplink transmission and downlink transmission may use a time divisionduplex (TDD) scheme, which performs transmission by using differenttimes, or may use a frequency division duplex (FDD) scheme, whichperforms transmission by using different frequencies.

An exemplary embodiment of the present invention can be used in resourceassignments, such as asynchronous wireless communication evolved to LTEand LTE-advanced via GSM, WCDMA, and HSPA, and synchronous wirelesscommunication evolved to CDMA, CDMA-2000, and Ultra-Mobile Broadband(UMB). However, aspects of the present invention are not limited to aspecific wireless communication field and shall be construed asincluding all technical fields to which the technical features describedherein can be applied.

A method for supporting a high data rate in a next generation wirelesscommunication system according to aspects of the present inventionallows the UE 10 or the eNB 20 to ensure a transmission/receptionbroadband bandwidth in uplink and downlink by using a plurality ofcomponent carriers (CCs). The plurality of CCs can be configured as onesystem band or system carrier. One CC can be regarded as one wirelesscommunication band before using a carrier aggregation.

FIG. 2 shows a case of simultaneously using 5 CCs having a frequencyband of 20 MHz or lower in a wireless communication system to anexemplary embodiment of the present invention. FIG. 2 shows the conceptof frequency extension in a carrier aggregation environment.

Referring to FIG. 2, the UE 10 can be camped on through all CCs, i.e., aCC1 to a CC5. If the UE 10 is camped on, the UE 10 establishessynchronization to the eNB 20, receives basic control information forcommunication with the eNB 20, and communication is possible in aspecific frequency band. The basic control information includes a masterinformation block (MIB), such as a physical broadcast channel (PBCH),and a system information block (SIB), such as a physical downlink sharedchannel (PDSCH). In particular, in case of an SIB type 2 (SIB2), anuplink (UL) cell bandwidth, a random access parameter, and a UL powercontrol parameter are present. Therefore, if the UE 10 is camped on theeNB 20, a parameter for using a random access channel (RACH) isreceived.

In addition, the UE 10 can basically perform random access to all CCs,i.e., the CC1 to the CC5. In particular, the UE 10 may perform randomaccess first to an LTE CC which has a high possibility of being used asan anchor carrier. The anchor carrier may also be referred to as aprimary component carrier (PCC). The remaining CCs other than the PCCmay also be referred to as a secondary component carrier (SCC). The PCCand the SCC are determined for each UE. For example, for a first UE, theCC1 may be the PCC and the remaining CCs may be the SCCs, and for asecond UE, the CC3 may be the PCC and the remaining CCs may be the SCCs.

Meanwhile, the anchor carrier may be defined as one of the CCs havingall or some functions described below.

-   -   Initial synchronization between a cell and a UE and        synchronization maintenance    -   Random access    -   System information reception for all or some CCs    -   Criterion on radio link failure (RLF) determination    -   Security related setup and management between the cell and the        UE    -   Non-access stratum (NAS) mobility setup and management    -   Criterion and control of a discontinuous reception (DRX)        operation for all or some CCs

In addition, the anchor carrier may be configured in a cell unit, a userunit, or a user group unit. The anchor carrier may also be referred toas a serving cell, a primary serving cell (PSC), a special cell, etc. Ananchor CC, i.e., the CC1, may be used as a criterion that indicateswhich carrier around the CC1 is in association with or communicationwith the UE and that reports which carrier is activated or deactivated.

Exemplary embodiments of the present invention provide an apparatus andmethod for constructing and assigning an activation group for a wirelesstransmission/reception operation of a UE by considering a deviceconfiguration condition of the UE, required service quality of anapplication program (e.g., an Internet Protocol (IP) based voicetelephony (i.e., Voice over IP (VoIP)), a video streaming service, afile transfer, web surfing, etc.), an amount of power consumption, userlocation information, a shadow area, a frequency selective channel, etc.

The eNB 20 may configure an activation group including at least one CCamong all CCs that can be received by the UE 10, and may transmitinformation for the activation group to the UE 10. This process isperformed according to a type and criterion to be described below.

This specific activation group can be classified into a controlinformation activation (sub) group that includes one group according toa CC including control information for the UE and a data informationactivation (sub) group that includes one group according to a CCincluding data information for the UE. The UE receives a CC of thecontrol information activation group or a CC of the data informationactivation group. A corresponding CC is activated in order for the UE toreceive the CC. If the CC belongs to the control information activationgroup or the data information activation group, the CC is activated. Onthe contrary, when the CC belongs neither to the control informationactivation group nor to the data information activation group, the CC isdeactivated.

The eNB may indicate activation/deactivation of a CC by including orexcluding the CC to or from the control information activation group orthe data information activation group. Information indicating whether aspecific CC belongs to the control information activation group or thedata information activation group is referred to as an activationindicator.

FIG. 3 shows a downlink control information activation group accordingto an exemplary embodiment of the present invention. Referring to FIG.3, signals are transmitted in a radio frame unit in each of all CCs,i.e., a CC1 to a CC5. In this case, the radio frame may consist of 10subframes, and one subframe may consist of two consecutive slots, i.e.,a slot 1 and a slot 2.

In a downlink scenario, the first three (or fewer) OFDM symbols of theslot 1 in the subframe correspond to a control region to which aphysical downlink control channel (PDCCH) is assigned, and the remainingOFDM symbols correspond to a data region to which a physical downlinkshared channel (PDSCH) is assigned. In addition to the PDCCH, a controlchannel, such as a physical control format indicator channel (PCFICH), aphysical hybrid automatic repeat request (HARM) indicator channel(PHICH), etc., can be assigned to the control region.

The UE 10 may decode control information transmitted through the PDCCHand thereafter may read data information transmitted through the PDSCHon the basis of the decoded control information. In this case, thecontrol information includes 3 OFDM symbols according to an exemplaryembodiment of the present invention. Meanwhile, the number of OFDMsymbols included in the control region in the subframe can be knownthrough the PCFICH.

The UE 10 may decode control information transmitted through the PDCCHof each CC in downlink in the presence of downlink control information(DCI), and may read data information transmitted through the PDSCH ofeach CC of downlink on the basis of the decoded control information.

A plurality of PDCCHs multiplexed for the plurality of UE 10 may betransmitted in the control region. The PDCCH is used to carry the DCI,such as scheduling determination and power control commands. Morespecifically, the DCI may include control information, such as downlinkscheduling assignments, uplink scheduling grants, power controlcommands, etc. Another type of control information corresponds to a sizeof another DCI message. Therefore, the DCI can be identified with adifferent DCI format. In this case, the DCI format corresponds to amessage size and usage.

One PDCCH carries one message through one of the DCI formats. Since theplurality of UEs 10 can be simultaneously scheduled on uplink anddownlink, a plurality of scheduling messages can be transmitted in eachsubframe. Since the respective scheduling messages are transmitted onseparate PDCCHs, the plurality of PDCCHs can be simultaneouslytransmitted in each eNB 20.

Referring again to FIG. 3, the DCI format of the PDCCH of each CC maytransmit control information, such as uplink grants and downlink grants,for a CC having the DCI format, e.g., a CC which is the same as the CC2of FIG. 3. In addition, the DCI format of the PDCCH of each CC maytransmit control information, such as uplink grants and downlink grants,not only for a CC having a DCI format of a PDCCH of a specific CC, i.e.,a CC which is the same as the CC2, but also at least one of other CCs,i.e., the CC1 and the CC3.

The DCI format of the PDCCH of each CC may transmit control information,such as uplink grants and downlink assignments, for only a CC (i.e., theCC3) having a DCI format of a PDCCH of a specific CC and at least oneanother CC (i.e., the CC5). In this case, the DCI format exists for eachof a plurality of CCs to transmit control information of the respectiveCCs through the PDCCH.

In the wireless communication system, among all receivable CCs, i.e.,the CC1 to the CC5, the eNB 20 determines a CC that is the same as theCC having the DCI format for the UE 10 or CCs (i.e., the CC2 and theCC3) that include control information (i.e., PDCCH) of at least oneother CCs as a control information activation group (also referred to asa PDCCH active set), and reports information on the PDCCH active set tothe UE 10. The PDCCH active set may also be referred to as a PDCCHmonitoring set.

Therefore, the UE 10 may receive control information (i.e., PDCCH) on aCC in the PDCCH active set, and thereafter may confirm a location of thePDSCH transmitted to the UE 10 by analyzing information in the controlinformation (i.e., PDCCH), and confirm data information (i.e., PDSCH) ofthe location indicated by the control information (i.e., PDCCH).

FIG. 4 shows a case in which a missing region is generated if data isreceived using a control information activation indicator of FIG. 3.

A location indicated by one control information (i.e., PDCCH) may be oneof all CCs, i.e., a CC1 to a CC5, which can be received by the UE 10,and thus the UE 10 performs a reception process for all CCs, i.e., theCC1 to the CC5. In this case, since the reception process is performedon all CCs, unnecessary battery consumption may occur in the UE 10.

For example, if the CCs respectively use bands of 700 MHz, 1.9 GHz, 2.1GHz, 3 GHz, and 5 GHz, the UE 10 must perform the reception process forall frequency bands.

Meanwhile, if the eNB 20 configures the control information activationgroup as shown in FIG. 3 by considering unnecessary power consumptionand transmits the configured control information activation group to theUE 10, the UE 10 may receive control information (i.e., PDCCH) regardinga CC of the control information activation group, and thereafter confirma location of data information (i.e., PDSCH) transmitted to the UE 10 byanalyzing information included in the control information (i.e., PDCCH)and confirm data information (i.e., PDSCH) of the location indicated bythe control information (i.e., PDCCH).

The UE 10 may confirm the location of the data information transmittedto the UE 10 if blind coding is performed on both a common search spaceand a UE-specific search space in a control region of CCs (i.e., the CC2and the CC3) belonging to the control information activation group. TheUE 10 may reduce a range of CCs to be blind decoded by using the controlinformation activation group received from the eNB 20. The number ofblind decoding attempts performed by the UE 10 to receive the controlinformation is linearly in proportion to the number of CCs included inthe control information activation group.

Meanwhile, the UE 10 may receive the control information according topredefined resources and transmission schemes (i.e., predefined mappingfrom previous signaling) on the basis of an assignment location ofprevious control information, an assignment location of previous data,etc.

Therefore, exemplary embodiments of the present invention includes amethod for configuring the control information activation group and thedata information activation group in downlink and for transmittinginformation on the configured activation groups to the UE in thewireless communication system.

FIG. 5 shows a control information activation group and a datainformation activation group in downlink according to an exemplaryembodiment of the present invention. Referring to FIG. 5, the eNB 20 mayconfigure the same CC as a CC having a DCI format for the UE 10 amongall receivable CCs (i.e., a CC1 to a CC5) or CCs (i.e., the CC2 and theCC4) including control information (i.e., PDCCH) of at least one ofother CCs as the control information activation group.

Further, the eNB 20 may configure CCs including data information (i.e.,PDSCH) indicated by the control information (i.e., PDCCH) of the controlinformation activation group as the data information activation group(also referred to as a PDSCH active set). For example, as shown in FIG.5, CCs (i.e., the CC1, the CC2, the CC4, and the CC5) including datainformation (i.e., PDSCH) indicated by control information of CCs (i.e.,the CC2 and the CC4) corresponding to the control information activationgroup may be configured as the PDSCH active set. The PDSCH active setmay also be referred to as a PDSCH monitoring set.

The eNB 20 transmits a control information activation indicator and adata information activation indicator to the UE 10. The UE 10 receivesthe control information activation indicator and data informationactivation indicator. The UE 10 may receive control information (i.e.,PDCCH) existing in CCs (i.e., the CC2 and the CC4) belonging to thecontrol information activation group by using the control informationactivation indicator, and thereafter confirm the data information (i.e.,PDSCH) of CCs (i.e., the CC1, the CC2, the CC4, and the CC5) belongingto the data information activation group by using the data informationactivation indicator without having to confirm a location of the PDSCHtransmitted to the UE 10 by analyzing information included in thecontrol information (i.e., PDCCH).

In this case, the eNB 20 may transmit the control information activationindicator and the data information activation indicator to the UE 10,and by using the received information, the UE 10 may receive only CCsbelonging to the control information activation group and the datainformation activation group. The UE 10 may perform blind decoding oncontrol information existing in the CCs belonging to the controlinformation activation group and confirm data information (i.e., PDSCH)of the CCs (i.e., the CC1, the CC2, the CC4, and the CC5) belonging tothe data information activation group.

Consequently, the UE 10 receives only the CCs belonging to the controlinformation activation group, e.g., the CC2 and the CC3. Therefore, amissing region in which data information cannot be received is notgenerated in the CCs belonging to the control information activationgroup, e.g., the CC1, the CC2, the CC4, and the CC5.

If the data information activation group is configured and used asdescribed above, a small number of CC are received and monitored, andthus a power consumption amount may be decreased, and an error caused bya time difference generated when analyzing data information by usingcontrol information may be decreased.

Parameters to be considered to construct the specific activation groupscan be classified into two types as follows.

First, the factors in determination of wireless communication capabilitywhen the eNB 20 intends to transmit data to the UE 10 in a wirelessfashion are factors that commonly have an effect on informationreliability for both control information and data information. Thefactors include a power characteristic classified into transmit power,interference power, and noise power; a radio frequency (RF) devicecharacteristic represented by an antenna pattern, the number ofantennas, an RF circuitry, or the like; a basebandtransmission/reception method and algorithm, such as OFDM, CDMA, channelcoding, MIMO processing, or the like; and a channel environmentexpressed by a surrounding environment, a user location, or the like.

Second, there are factors having different affects according to aninformation characteristic. For example, the control information and thedata information may be transmitted using different transmission methodsas they are received by the UE 10 for different purposes, and a qualityof service (QoS) value, such as a required data rate per unit time, maybe different between the control information and the data information.In other words, QoS and a method for transmitting the data informationmay change according to a required service of an application program ofthe UE 10, but the control information may not be significantly affectedby such a change.

In another aspect, if a user desires to receive a consistent service butsystem reliability is low due to a resource usage rate of the system, asurrounding environment change, etc., transmission and assignment of thecontrol information for compensating this may change, whereas there maybe no effect when transmitting the data information.

In this case, the data information activation group may be a sub-groupof the control information activation group, or the control informationactivation group may be a sub-group of the data information activationgroup, or the control information activation group and the datainformation activation group may have no inclusion relation.

In order to decrease a power consumption amount of the UE 10, thecontrol information activation group may be the sub-group of the datainformation activation group. If only the data information activationgroup is constructed without having to configure the control informationactivation group, only CCs belonging to the data information activationgroup are considered when the control information is assigned. That is,if the control information activation group is not constructed, thecontrol information may be transmitted by using a CC in the constructeddata information activation group.

In addition, if the inclusion relation is not satisfied between thecontrol information activation group and the data information activationgroup, an activated activation group of the UE 10 can be defined as aunion set of the two groups.

FIG. 6 is a flowchart for configuring a control information activationgroup according to an exemplary embodiment of the present invention.FIG. 7 shows a structure of an activation group for each layer accordingto an exemplary embodiment of the present invention.

Referring to FIG. 6 and FIG. 7, only CCs capable of transmitting controlinformation are first selected from all CCs to configure the selectedCCs as a primary preliminary activation group (operation S610). As shownin FIG. 7, only CCs (i.e., a CC1, a CC3, and a CC4) capable oftransmitting the control information are selected from all CCs (i.e., aCC1 to a CC5) to configure the selected CCs as the primary preliminarycontrol information activation group (operation S610).

Next, among the CCs belonging to the configured primary preliminaryactivation group, CCs that can be transmitted or received by the UE 10are configured as a secondary preliminary control information activationgroup by considering a device configuration condition of the UE 10 suchas (1) an operational frequency range of an RF device and/or (2) thenumber of antennas (operation S620). As shown in FIG. 7, among theprimary preliminary control information activation group (i.e., the CC1,the CC3, and the CC4), CCs (i.e., the CC1 and the CC4) that can betransmitted/received by the UE 10 are configured as the secondarypreliminary control information activation group by considering, forexample, the device configuration condition of the UE 10.

Next, among characteristics of CCs of the secondary preliminaryactivation group, one or more preferred assignment activation groups canbe finally configured by considering several factors, i.e., (1) acontrol information resource usage rate, (2) transmit power, (3) receivepower in the UE, (4) interference power or noise power or a sum of thetwo power levels, (5) a ratio of receive power to interference power inthe UE or a ratio of receive power to interference power and noisepower, and/or (6) a format of transmissible control information(operation S630). A group of the configured preferred assignment CCs isreferred to as an activation group for the control information. As shownin FIG. 7, among the secondary preliminary control informationactivation group (i.e., the CC 1 and the CC4), the preferred assignmentCC (i.e., the CC1) is configured as the preferred assignment controlinformation activation group by considering a CC characteristic of thesecondary preliminary control information activation group (i.e., theCC1 and the CC4).

Next, the control information is assigned to the configured preferredassignment CC (i.e., the CC1) (operation S640).

Next, it is determined whether there is remaining control information tobe assigned to the preferred assignment CC (operation S650). In thiscase, if there is the remaining control information to be assigned tothe preferred assignment CC, a process of adding the preferredassignment CC (i.e., the CC4) in the same manner as operation S630except for the previously configured preferred assignment CC (i.e., theCC1) (operation S660) and a process of assigning the control informationto preferred assignment CC added (operation S640) may be repeated untilthe control information to be transmitted is entirely transmitted.

In this case, a maximum amount of information that can be assigned tothe preferred assignment CC is derived from a cost function defined byconsidering factors considered if the secondary preliminary controlinformation activation group is configured and factors used when thepreferred assignment CC is configured. The cost function may have anoption such as (1) minimization of the number of CCs (i.e., decrease ofpower consumption) and/or (2) maximization of the number of CCs (i.e.,maximization of a diversity gain, ensuring of system reliability, etc).

Next, if there is no remaining control information to be assigned to thepreferred assignment CC, the preferred assignment CCs (i.e., the CC1 andthe CC4) to which the control information is assigned are configured asthe control information activation group (operation S670).

FIG. 8 is a flowchart for configuring a data information activationgroup according to an exemplary embodiment of the present invention.Referring to FIG. 8, among all CCs, only CCs capable of transmittingdata information are configured as a primary preliminary datainformation activation group (operation S710).

Next, among the CCs configured in the primary preliminary datainformation activation group, CCs that can be transmitted or received bythe UE 10 are configured as a secondary preliminary data informationactivation group by considering a device configuration condition of theUE 10, such as (1) an operational frequency range of an RF device, (2)the number of antennas, (3) memory capacity in the device, and/or (4) amaximum operational clock count (operation S720).

Next, among characteristics of CCs configured in the secondarypreliminary data information activation group, one or more preferredassignment CCs can be configured by considering several factors, i.e.,(1) a control information resource usage rate, (2) transmit power, (3)receive power in the UE, (4) interference power or noise power or a sumof the two power levels, (5) a ratio of receive power to interferencepower in the UE or a ratio of receive power to interference power andnoise power, (6) a bandwidth, and/or (7) a presence/absence of controlinformation transmission (operation S730).

Next, the data information is assigned to the configured preferredassignment CC (operation S740).

Next, it is determined whether there is remaining data information to beassigned to the preferred assignment CC (operation S750). In this case,if there is the remaining data information to be assigned to thepreferred assignment CC, a process of adding the preferred assignment CCin the same manner as operation S730 except for the previouslydetermined preferred assignment CC (operation S760) and a process ofassigning the data information to the preferred assignment CC added(operation S740) may be repeated until the data information to betransmitted is entirely transmitted.

In this case, a maximum amount of information that can be assigned tothe preferred assignment CC is derived from a cost function defined byconsidering factors considered when the secondary preliminary datainformation activation group is configured and factors used when thepreferred assignment CC is configured. The cost function may have anoption such as (1) minimization of the number of CCs (i.e., decrease ofpower consumption) and/or (2) maximization of the number of CCs (i.e.,maximization of a diversity gain, ensuring of system reliability, etc).

Next, if there is no remaining data information to be assigned to thepreferred assignment CC, the preferred assignment CCs to which the datainformation is assigned are configured as the data informationactivation group (operation S770).

Meanwhile, the eNB 20 of FIG. 6, FIG. 7, and FIG. 8 or a scheduler ofthe eNB 20 may configure a specific activation group, for example, thecontrol information activation group and the data information activationgroup, in a case in which a specific time elapses periodically, a casein which a specific external condition for starting to construct thespecific activation group is satisfied or an event occurs, and a case inwhich a specific internal condition for starting to construct thespecific activation group is satisfied or an event occurs.

In this case, the case in which the specific external condition forstarting to construct the specific activation group or the event occursmay be a case in which a power characteristic of the UE decreases tobelow a reference threshold or a channel condition deteriorates to belowa threshold or a required service of an application program of the UE 10changes.

The case in which the specific internal condition for starting toconstruct the specific activation group or the event occurs may be acase in which system reliability decreases due to a resource usage ratein the system, a surrounding environment change, etc.

FIG. 9 shows an example of transmitting an activation indicatorindividually for each CC of an activation group according to anexemplary embodiment of the present invention.

Referring to FIG. 9, the eNB 20 may transmit the activation indicator tothe UE 10. The activation indicator is information that individuallyindicates activation and deactivation of respective CCs belonging to theactivation group.

As shown in FIG. 9, among all CCs (i.e., a CC1 to a CC5), only CCs(i.e., the CC1, the CC3, and the CC4) capable of transmitting controlinformation are selected to be configured as a primary preliminaryactivation group. In this case, the eNB 20 deactivates CCs (i.e., theCC2 and the CC5) which are not configured as the primary preliminaryactivation group. That is, the eNB 20 transmits to the UE 10 anactivation indicator by setting a bit of the activation indicator to “1”if the bit corresponds to a CC index of a CC that belongs to the primarypreliminary activation group and thus is activated and by setting thebit to “0” if the bit corresponds to a CC index of a CC that does notbelong to the primary preliminary activation group and thus isdeactivated.

The activation indicator may be generated on the basis of the primarypreliminary activation group, or may be generated on the basis of asecondary preliminary activation group. For example, ifactivated/deactivated CCs are expressed by 5 bits according to whetherthey belong to the primary preliminary activation group of FIG. 9, theactivation indication is set to “10110”. In addition, ifactivated/deactivated CCs are expressed by 5 bits according to whetherthey belong to the secondary preliminary activation group of FIG. 9, theactivation indication is set to “10010”.

Herein, the wireless communication system is a system that maysimultaneously use up to 5 CCs. In addition, if the wirelesscommunication system is a system supporting M CCs (where M≧5), theactivation indicator corresponding to the CC may be configured with mbits. For example, if the UE supports one PSC and 7 SSC, that is, inorder to indicate activation/deactivation of 8 CCs, the activationindicator may be configured to have a length of 8 bits. In this case,according to a characteristic of the PSC, an activation indicator forthe PSC may not be configured.

FIG. 10 is a flowchart for transmitting an activation indicator in aneNB according to an exemplary embodiment of the present invention.

Referring to FIG. 10, in a wireless communication environment, the UE 10may establish synchronization with the eNB 20 and receive a masterinformation block (MIB) through a physical broadcast channel (PBCH) in aspecific frequency band, or receive a system information block (SIB)through a PDSCH. Through this process, the UE 10 exchanges basic controlinformation for communication with the eNB 20 and thus can be camped onto enter a state in which communication with the eNB 20 is possible.

The eNB 20 or the scheduler of the eNB 20 collects information that canbe confirmed and used to construct or configure a control informationactivation group or a data information activation group through thecamp-on process (operation S1010). Examples of the information include adevice characteristic of the UE 10, e.g., a power characteristic, an RFdevice characteristic, a baseband transmission/reception scheme, analgorithm in use, an available CC, a supportable service, the number ofantennas, etc.

Next, the eNB 20 or the scheduler of the eNB 20 configures an activationgroup according to the activation group construction or configurationmethod described above with reference to FIG. 6, FIG. 7, and FIG. 8 byusing the information collected in the camp-on process and informationpreviously known to the eNB 20 (operation S1020).

Next, the eNB 20 or the scheduler of the eNB 20 transmits the activationindicator configured in operation S1020 to the UE 10 (operation S1030).The eNB 20 may transmit to the UE 10 the activation indicator in whichactivated/deactivated CCs are expressed by 5 bits according to whetherthe CCs belong to the activation group as described above with referenceto FIG. 9.

In addition, if 8 serving cells are supported, the activation indicatorconfigured to have the length of 8 bits may be transmitted to the UE 10.Herein, since the PSC is always in the activation state, a 7-bitactivation indicator may be transmitted for the SSC which is notconfigured with the activation indicator for the PSC.

The activation indicator may be transmitted to the UE 10 through thePDCCH or the PDSCH.

Further, the eNB 20 may transmit the activation indicator by using radioresource control (RRC) signaling. Furthermore, after constructing theactivation indicator, the eNB 20 may transmit the activation indicatorby using a higher layer (L2 or higher) signaling, or by using an L1signaling, or by combining the L1 signaling and the higher layer (L2 orhigher) signaling. In this case, the constructed activation indicatorcan be partially or entirely transmitted by selectively applying one ofthe signaling mechanisms according to a condition.

The higher layer (L2 or higher) is a higher layer of a physical layer(i.e., an L1 layer), for example, an L2 layer including a medium accesscontrol (MAC) layer or a radio link control (RLC) layer, a packet dataconvergence protocol (PDCP) layer, and a broadcast/multicast control(BMC) layer, and an L3 layer including a radio resource control (RRC)layer, etc.

FIG. 11 is a schematic view of a transmitter to transmit an activationindicator according to an exemplary embodiment of the present invention.Referring to FIG. 11, a transmitter 1100 of the activation indicatorincludes a transceiver 1110 and a control unit 1120. The control unit1120 includes an activation group configuration unit 1124, and anactivation indicator generation unit 1122. And the transceiver 1110includes a message transmission unit 1112, and a message reception unit1114.

As described in FIG. 6 to FIG. 10, the activation group configurationunit 1124 confirms CCs that can be activated by using informationcollected in a camp-on process and information previously known to theeNB 20. Further, the activation group configuration unit 1124 configuresan activation group from CCs that satisfy a condition among theconfirmed CCs.

The activation indicator generation unit 1122 generates the activationindicator on the basis of the configured activation group as configuredby the activation group configuration unit 1124, and delivers thegenerated activation indicator to the message transmission unit 1112.

The message transmission unit 1112 receives the activation indicatorfrom the activation indicator generation unit 1122, and transmits theactivation indicator to the UE 10. In this case, as described above, thetransceiver 1110 may transmit information on the configured CC groupthrough a PDCCH or a PDSCH, or may transmit the information by usinghigher layer (L2 or higher) signaling or by using L1 signaling or bycombining the L1 signaling and the higher layer (L2 or higher)signaling.

If the message transmission unit 1112 transmits the activation indicatorby using the L2 signaling, the activation indicator is a MAC protocoldata unit (PDU), and is generated by the activation indicator generationunit 1122. A method for generating the activation indicator in a MAC PDUformat by the activation indicator generation unit 1122 will bedescribed below in detail with reference to FIG. 16.

The message reception unit 1114 receives information required toconfigure a control information activation group or a data informationactivation group from the UE 10 by performing the camp-on process withrespect to the UE 10. The information is a device characteristic of theUE 10 and, for example, includes an RF device characteristic, a basebandtransmission/reception scheme, an algorithm in use, an available CC, asupportable service, the number of antennas, etc. The message receptionunit 1114 delivers the received information to the activation groupconfiguration unit 1122.

Hereinafter, an example of using OFDM and MIMO in the wirelesscommunication system according to an exemplary embodiment of the presentinvention will be describe with reference to FIG. 12. FIG. 12 shows asignal generation structure of a downlink physical channel fortransmitting an activation indicator according to an exemplaryembodiment of the present invention.

Referring to FIG. 12, a signal generation structure 1200 of a downlinkphysical channel includes a scrambler 1210, a modulation mapper 1220, alayer mapper 1230, a precoder 1240, a resource element mapper 1250, andan OFDM signal generator 1260.

The activation indicator is input in a codeword format via channelcoding in downlink. In this case, bits which are input in the codewordformat via the channel coding in downlink are scrambled by the scrambler1210 and are then input to the modulation mapper 1220.

The modulation mapper 1220 modulates the scrambled bits into acomplex-valued modulation symbol. The layer mapper 1230 maps thecomplex-valued symbol to one or a plurality of transmission layers.Thereafter, on respective transport channels of an antenna port, theprecoder 1240 performs precoding on the complex-valued modulationsymbol. Thereafter, the resource element mapper 1250 maps thecomplex-valued modulation symbol for each of antennas, for example, #1to #8, to corresponding resource elements. In this case, in the signalgeneration structure 1200 of the message transmission unit 1115,resources of an OFDM symbol (x-axis) and a subcarrier location (y-axis)are assigned by a predefined rule as described above, and aremultiplexed with an eNB transmission frame at predefined frame timing.

Thereafter, the OFDM signal generator 1260 generates an OFDM symbol foreach antenna in a complex time domain. The OFDM symbol in the complextime domain is transmitted through the antenna port.

FIG. 13 is a flowchart for receiving an activation indicator accordingto an exemplary embodiment of the present invention. Referring to FIG.13, in operation S1310, the UE 10 receives the activation indicator. Inoperation 1320, the UE 10 activates at least one deactivated CC on thebasis of the received activation indicator, or deactivates at least oneactivated CC. In this case, the activation indicator can be expressed by5 bits.

Meanwhile, if the UE supports 8 serving cells, an 8-bit activationindicator may be received. Herein, the UE may receive the 7-bitactivation indication for the SSC which is not configured with theactivation indicator for the PSC.

In operation S1330, the UE receives a PDCCH or PDSCH transmitted fromthe eNB 20 by using the at least one activated CC, and then demodulatesand analyzes the received PDCCH or PDSCH. In other words, the UE cannotreceive a PDCCH or a PDSCH by using at least one deactivated CC. Inaddition, since uplink scheduling grants are impossible when using thedeactivated CC, the UE cannot perform uplink data transmission by usingthe deactivated CC.

Operation S1330 will be described in detail. It is assumed herein thatthe UE supports 8 serving cells for example. In this case, if theactivation group is based on reception of the PDCCH between the eNB andthe UE, the UE receives the PDCCH by using a corresponding SSC indicatedas the activation state by confirming the 8-bit activation indicator,and then demodulates and analyzes the received control information.

In addition, if the activation group is based on reception of the PDSCHbetween the eNB and the UE, the UE receives the PDSCH by using thecorresponding SSC indicated as the activation state by confirming the8-bit activation indicator, and then demodulates and analyzes thereceived data information.

In addition, if the activation group is based on reception of at leastone of the PDCCH and the PDSCH between the eNB and the UE, the UEreceives the PDCCH or the PDSCH by using the corresponding SSC indicatedas the activation state by confirming the 8-bit activation indicator.Then, the UE demodulates and analyzes the received control informationor data information.

Meanwhile, as to the PDCCH, the UE may selectively receive anddemodulate the PDCCH by using a specific serving cell among thedeactivated serving cells. Herein, demodulation is a process ofconfirming whether the received PDCCH is a PDCCH for the UE, andincludes cyclic redundancy check (CRC). In this case, the UE does notanalyze the control information included in the PDCCH received by usingthe serving cell in the deactivation state.

Meanwhile, the UE may receive the activation indicator by performing RRCsignaling. Alternatively, the UE may receive the activation indicator byusing higher layer (L2 or higher) signaling or by using L1 signaling orby combining the L signaling and the higher layer (L2 or higher)signaling.

By using a confirmed CC, the UE 10 confirms a region in which datainformation received and a region in which control information isreceived. In this case, the region in which the control information isreceived can be used to confirm the region in which the data informationis received.

FIG. 14 shows a receiver to receive an activation indicator according toan exemplary embodiment of the present invention. Referring to FIG. 14,a receiver 1400 of the UE in the wireless communication system includesa reception processing unit 1410, an activation group confirmation unit1420, and an information analysis unit 1430.

A signal received through each antenna port is converted into a signalof a complex time domain by the reception processing unit 1410.

The activation group confirmation unit 1420 extracts a serving cellindex of a serving cell to be configured in the UE from the convertedsignal by using RRC signaling of the eNB. Further, the activation groupconfirmation unit 1420 extracts index mapping information and theactivation indicator, which indicates activation/deactivation of a CCbased on a specific serving cell index, from a MAC message of the eNB.

The activation indicator may be constructed in a format of a bitmaphaving a specific length. The length of the bitmap may be determinedvariously, for example, 4 bits, 8 bits, etc. Each bit of the bitmapcorresponds to or is mapped to a unique serving cell index according toits position. A position of a specific bit of the bitmap may be fixedlydetermined by an index of a supportable component carrier. The servingcell may be a primary serving cell (PSC) or a secondary serving cell(SSC). Further, the PSC may be fixedly determined.

For example, if the bitmap length is 8 bits, the serving cell index ofthe serving cell to be configured in the UE is mapped to a bit in aunique position on the bitmap of the activation indicator. In this case,a specific position to which the serving cell index uniquely correspondsmust be previously known between the UE and the eNB without additionalsignaling.

For another example, when the bitmap length is 4 bits, the serving cellindex of the serving cell to be configured in the UE is mapped to thebitmap after being ordered according to its sequence. For example, a bitwith a lowest priority indicates activation/deactivation of a CC basedon a smallest serving cell index among serving cells configured in theUE. Further, a bit with a next priority indicatesactivation/deactivation of a CC based on a second smallest serving cellindex among the serving cells configured in the UE. In this case, aspecific order according to which the serving cell index of the servingcells to be configured in the UE is ordered and mapped to the bitmapmust be previously known between the UE and the eNB without additionalsignaling.

For another example, if the bitmap length is 4 bits, a specific bitposition on the bitmap and corresponding to the serving cell index ofthe serving cell to be configured in the UE may be signaled from the eNBto the UE.

Detailed descriptions on the activation indicator and the index mappinginformation will be described below.

The activation group confirmation unit 1420 confirms CCs which aregrouped in correspondence with specific information. The activationgroup may differ depending on the specific information.

The information analysis unit 1430 confirms and analyzes information oneach CC in the confirmed activation group and thus obtains controlinformation or data information. The information analysis unit 1430 mayreceive control information (i.e., PDCCH) existing in a correspondingcontrol information activation group and thereafter may confirm datainformation (i.e., PDSCH) indicated by the control information (i.e.,PDCCH).

Further, the information analysis unit 1430 may receive only CCsbelonging to the control information activation group and the datainformation activation group by using the information, so that controlinformation existing in a CC belonging to the control informationactivation group is blind decoded and data information of a CC belongingto the data information activation group is confirmed.

Furthermore, the information analysis unit 1430 confirmsactivation/deactivation of each CC from the extracted activationindicator. Accordingly, the receiver 1400 monitors or blind-decodes orreceives selectively only a control channel of an activated CC, and doesnot monitor or blind-decode or receive a deactivated CC. When a specificdownlink CC is deactivated, the receiver 1400 no longer receives a PDCCH(downlink assignment and uplink grants) of a corresponding serving cell.In addition, when the specific downlink CC is deactivated under a crosscarrier scheduling environment, the receiver 1400 no longer has toreceive downlink assignments related to a UE-specific PDCCH searchspace.

The receiver 1400 of the UE of the wireless communication system is anapparatus for receiving a signal transmitted from the messagetransmission unit 1112 described above with reference to FIG. 11.Therefore, the receiver 1400 consists of elements for performing signalprocessing which is reverse to that of the transmitter 1100.

Therefore, it shall be construed that unspecified elements of thereceiver 1400 can be replaced with respective elements for performingthe signal process which is reverse to that of FIG. 11. In addition,unspecified operations of the transmitter 1100 can be performed by beingconstructed with elements for performing operations which are reverse tothose of the receiver 1400 of FIG. 14.

Hereinafter, a definition and type of a serving cell and an activationindicator will be described in greater detail.

The serving cell is a cell in which the UE is currently receiving aservice. A neighbor cell is a cell geographically neighboring to theserving cell or a cell neighboring on a frequency band. In order toperform transmission and reception of packet data by using a specificcell, the UE must first complete configuration of a specific cell or CC.Herein, the configuration is a state in which system informationrequired for data transmission/reception is completely received for acell or CC.

For example, the configuration may include an overall process ofreceiving common physical layer parameters required for the datatransmission/reception, or MAC layer parameters, or parameters requiredfor a specific operation in an RRC layer. Thus, when the cell or the CCis completely configured, the cell or the CC is in a state in whichpacket transmission/reception becomes possible immediately as soon asreceiving signaling information indicating that packet data can betransmitted.

Meanwhile, the cell in the completely configured state may exist in anactivation or deactivation state. The reason of dividing theconfiguration state into the activation state and the deactivation stateis to decrease battery consumption of the UE by allowing the UE tomonitor or receive a control channel (i.e., PDCCH) and a data channel(i.e., PDSCH) only when in the activation state. Herein, an initialstate related to activation immediately after the configuration iscomplete is the deactivation state.

The activation is a state in which traffic data is transmitted orreceived or in a ready state. The UE may monitor, blind-decode, orreceive the control channel (i.e., PDCCH) and the data channel (i.e.,PDSCH) of an activated cell in order to confirm a resource (e.g.,frequency, time, etc.) assigned to the UE.

The deactivation is a state in which traffic data transmission orreception is impossible, and measurement or minimum informationtransmission/reception is possible. The UE may receive systeminformation (SI) required to receive a packet from a deactivation cell.On the other hand, the UE does not monitor, blind-decode, or receive thecontrol channel (i.e., PDCCH) and the data channel (i.e., PDSCH) of thedeactivation cell to confirm the resource (e.g., frequency, time, etc.)assigned to the UE.

FIG. 15 is a diagram for explaining the concept of a primary servingcell (PSC) and a secondary serving cell (SSC). Referring to FIG. 15, aPSC 1505 is one serving cell for providing security inputs and NASmobility information in an RRC establishment or re-establishment state.According to UE capabilities, at least one cell can be constructed to bea group of serving cells together with the PSC 1505. The at least onecell is referred to as an SSC 1520.

Therefore, the group of the serving cells configured for one UE may beconstructed only with one PSC 1505, or may be constructed with one PSC1505 and at least one SSC 1520.

Intra-frequency neighbor cells 1500 and 1510 of the PSC 1505 and/orintra-frequency neighbor cells 1515 and 1525 of the SSC 1520 belong tothe same carrier frequency. Inter-frequency neighbor cells 1530, 1535,and 1540 of the PSC 1505 and the SSC 1520 belong to different carrierfrequencies.

A downlink CC corresponding to the PSC 1505 is referred to as a downlinkprimary component carrier (DL PCC). An uplink CC corresponding to thePSC 1505 is referred to as an uplink primary component carrier (UL PCC).A downlink CC corresponding to the SSC 1520 is referred to as a downlinksecondary component carrier (DL SCC). An uplink CC corresponding to theSSC 1520 is referred to as an uplink secondary component carrier (ULSCC). One serving cell may correspond to only one DL CC, or maycorrespond to both the DL CC and the UL CC.

A PCC is a CC in which the UE initially establishes a connection (or RRCconnection) among several CCs. The PCC serves as a connection (or RRCconnection) for signaling with respect to a plurality of CCs, and is aspecial CC for managing UE context which is connection informationrelated to the UE. Further, when the PCC establishes the connection withthe UE and thus is in an RRC connected mode, the PCC always exists in anactivation state.

The SCC is a CC assigned to the UE other than the PCC. The SCC is anextended carrier for additional resource assignment, etc., in additionto the PCC, and can be divided into an activation state and adeactivation state. The SCC is initially in the deactivation state.

The PSC 1505 and the SSC 1520 have the following characteristics.

First, the PSC 1505 is used for Physical Uplink Control Channel (PUCCH)transmission.

Second, the PSC 1505 is activated always, whereas the SSC 1520 isactivated/deactivated according to a specific condition.

Third, if the PSC 1505 experiences a radio link failure (RLF), an RRCreconnection is triggered, whereas if the SSC 1520 experiences the RLF,the RRC reconnection is not triggered.

Fourth, the PSC 1505 may change by a security key change or a handoverprocess accompanied by a random access channel (RACH) process.

As such, reconfiguration, adding, and removal processes of the SSC 1520can be performed by the RRC layer. When the SSC 1520 is newly added, RRCsignaling can be used to transmit system information of a dedicated SSC.

Hereinafter, an activation group is defined as a group including atleast one of a control information activation group and a datainformation activation group. Further, an activation indicator isdefined as information for indicating an activated CC and/or adeactivated CC on the basis of the activation group. In another aspect,the activation indicator is defined as information for indicating a CCto be monitored by the UE and a CC not necessarily monitored by the UE.The activation indicator indicates activation and deactivationindividually for each CC belonging to the activation group. As describedabove, a DL CC may construct one serving cell, and the DL CC and a UL CCmay construct one serving cell by being linked with each other.

Therefore, activation/deactivation of the CC is identical to the conceptof activation/deactivation of the serving cell. For example, if it isassumed that a serving cell 1 is constructed with a DL CC1, activationof the serving cell 1 implies activation of the DL CC1. If it is assumedthat a serving cell 2 consists of a DL CC2 and a UL CC2 with establishedconnections, activation of the serving cell 2 implies activation of theDL CC2 and the UL CC2. Further, a PSC corresponds to a PCC, and an SSCcorresponds to an SCC.

FIG. 16 shows a MAC protocol data unit (PDU) including an activationindicator according to an exemplary embodiment of the present invention.The activation indicator included in the MAC PDU is applied to both Case1 and Case 2. The MAC PDU can also be referred to as a transport block(TB).

Referring to FIG. 16, a MAC PDU 1600 includes a MAC header 1610, one ormore MAC control elements 1620, . . . , 1625, one or more MAC servicedata units (SDUs) 1630-1, . . . , 1630-m, and a padding 1640.

The MAC control elements 1620 and 1625 are a control message generatedby a MAC layer.

The MAC SDUs 1630-1, . . . , 1630-m are the same as an RLC PDU deliveredin a radio link control (RLC) layer. The padding 1640 is a specificnumber of bits appended to allow the MAC PDU to have a specific size.The MAC control elements 1620, . . . , 1625, the MAC SDUs 1630-1, . . ., 1630-m, and the padding 1640 are also collectively referred to as aMAC payload.

The MAC header 1610 includes one or more sub-headers 1610-1, 1610-2, . .. , 1610-K, each of which corresponds to one MAC SDU or one MAC controlelement (MAC CE) or a padding. The MAC CE may include a leastsignificant bit (LSB) by which the serving cells may be sorted. Further,the LSB may include an indicator of the PSC. An order of the sub-headers1610-1, 1610-2, . . . , 1610-K is identical to an order of correspondingMAC SDUs, MAC control elements, or paddings in the MAC PDU 1600.

Each of the sub-headers 1610-1, 1610-2, . . . , 1610-K may include 4fields, i.e., R, R, E, and LCID, or may include 6 fields, i.e., R, R, E,LCID, F, and L. A sub-header including the 4 fields is a sub-headercorresponding to the MAC control element or the padding. A sub-headerincluding the 6 fields is a sub-header corresponding to the MAC SDU.

The logical channel ID (LCID) field is an identification field foridentifying a logical channel corresponding to the MAC SDU or foridentifying a type of the MAC control element or the padding. The LCIDfield may have a length of 5 bits.

For example, the LCID field identifies whether a corresponding MACcontrol element is a surplus power MAC control element for transmittingsurplus power, whether it is a feedback request MAC control element forrequesting feedback information to the UE, whether it is a discontinuousreception (DRX) command MAC control element regarding a discontinuousreception command, and whether it is a contention resolution identityMAC control element for contention resolution between UEs.

In addition, according to an exemplary embodiment of the presentinvention, the LCID field can identify whether the corresponding MACcontrol element is a MAC control element including the activationindicator. One LCID field exists for each of the MAC SDU, the MACcontrol element, or the padding. Table 1 shows an example of the LCIDfield.

TABLE 1 Index LCID values 00000 CCCH 00001-01010 Identity of the logicalchannel 01011-10111 Reserved 11000 UL CC activation/deactivation 11001DL CC activation/deactivation 11010 Power Headroom Report 11011 C-RNTI11100 Truncated BSR 11101 Short BSR 11110 Long BSR 11111 Padding

Referring to Table 1, an LCID field value of ‘11000’ indicates that thecorresponding MAC control element is a MAC control element including anactivation indicator related to activation/deactivation of a UL CC. Inaddition, an LCID field value of ‘11001’ indicates that thecorresponding MAC control element is a MAC control element including anactivation indicator related to activation/deactivation of a DL CC.Table 1 shows a case in which the UL CC and the DL CC are independentlyactivated/deactivated.

However, activation/deactivation of the UL CC may be determineddepending on activation/deactivation of the DL CC, which is shown inTable 2 below. Table 2 shows another example of the LCID field.

TABLE 2 Index LCID values 00000 CCCH 00001-01010 Identity of the logicalchannel 01011-11000 Reserved 11001 CC activation/deactivation 11010Power Headroom Report 11011 C-RNTI 11100 Truncated BSR 11101 Short BSR11110 Long BSR 11111 Padding

Referring to Table 2, an LCID field value of ‘11001’ indicates that thecorresponding MAC control element is a MAC control element including theactivation indicator, and this concurrently indicatesactivation/deactivation of the DL CC and the UL CC.

That is, activation/deactivation of a DL CC and a UL CC with connectionsestablished by the SIB2 is indicated, i.e., activation/deactivation ofthe serving cell is indicated. Herein, since the PSC is always in theactivation state, activation/deactivation of the serving cell indicatesactivation/deactivation of the SSC.

The activation indicator is information transmitted from the eNB to theUE, and may be a message generated in a MAC layer or a message generatedin an RRC layer. By referring the activation indicator, the UE can beaware of which CC will be activated among all CCs that can be providedby the eNB or among CCs configured in a UE-specific manner.

However, since the PCC is a CC used as a criterion in communicationusing multiple CCs, the PCC is activated, generally, for the purpose ofsynchronization maintenance, system information reception, etc. In thiscase, the eNB and the UE may implicitly agree that the PCC is activatedalways (hereinafter, Case 1). In addition, a case of explicitlyindicating activation/deactivation of a CC even if the CC is the PCC mayalso be considered (hereinafter, Case 2). In Case 1, the activationindicator does not have to explicitly indicate activation of the PCC.Therefore, the UE operates by regarding that the PCC is activated,unless there is a special condition.

On the other hand, in Case 2, the activation indicator explicitlyindicates activation of the PCC. Since different activation indicatorsare used in Case 1 and Case 2, each case will be separately describedhereinafter.

1. Structure of Activation Indicator for Case 1

The activation indicator for Case 1 explicitly indicatesactivation/deactivation of an SSC. However, the activation indicator forCase 1 is constructed under the premise that a PSC is basicallyactivated. Therefore, even if the activation indicator for Case 1 doesnot additionally indicate activation/deactivation of the PSC, the UErecognizes activation of the PSC.

FIG. 17 shows a MAC control element including an activation indicatoraccording to an exemplary embodiment of the present invention. Here, thenumber of SSCs supportable in the system is equal to the number of bitsof the MAC control element including the activation indicator, and allsupportable SSCs are configured in the UE.

Referring to FIG. 17, a MAC control element 1700 including theactivation indicator has a length of 8 bits, and will be hereinafterreferred to as an activation indication MAC control element. Bits atrespective positions of the activation indication MAC control element1700 correspond to indices of SSCs in a one-to-one manner. For example,a serving cell index 1 corresponds to an 8^(th) bit from the left, and aserving cell index 2 corresponds to a 7^(th) bit from the left. Herein,the serving cell index is a serving cell index for an SSC because a PSCis implicitly regarded as being activated between the UE and the eNB andthus the PSC is not additionally included in the activation indicator.An index of the PSC is always given a specific value, and it is assumedherein that the index is given 0. Therefore, the serving cells areindexed with 1, 2, 3, . . . , 8, which are the remaining indices otherthan 0, i.e., the index of the PSC. Herein, the index of the servingcell may be a logical index determined relatively for each UE, or may bea physical index for indicating a cell of a specific frequency band.

Since the activation indication MAC control element 1700 has a length of8 bits, the activation indicator can indicate indices of 8 SSCs intotal. That is, the activation indicator can cover up to 8 CCs capableof indicating activation/deactivation.

Here, all supportable SSCs are configured in the UE. In this case, 8SSCs are configured in the UE. The activation indication MAC controlelement 1700 is ‘11001001’, and respective bits correspond to servingcell indices {8, 7, 6, 5, 4, 3, 2, 1} from the left. Therefore, theactivation indicator indicates activation of CCs corresponding to theserving cell indices {1, 4, 7, 8} and indicates deactivation of CCscorresponding to the serving cell indices {2, 3, 5, 6}. Herein, sincethe serving cell index 0 indicates a PSC, even though it is notindicated by the activation indication MAC control element 1700, the PSCis implicitly regarded as being activated. An order of a serving cellindex corresponding to a position of each bit of the activationindication MAC control element 1700 is for exemplary purposes only, andthe serving cell index does not have to be arranged in the order of FIG.17 and thus may be arranged in another order.

However, if there is no additional signaling, the UE and the eNB have toknow an order according to which each serving cell index corresponds toeach bit of the activation indication MAC control element 1700. Theorder is an order according to which a serving cell index of a servingcell configured in the UE is mapped to each bit of the activationindication MAC control element 1700. For example, a bit with a lowestpriority indicates activation/deactivation of a CC based on a lowestserving cell index among serving cells configured in the UE. A bit witha next priority indicates activation/deactivation of a CC based on asecond lowest serving cell index among the serving cells configured inthe UE. The order is not additionally reported by the eNB to the UE, andis determined by the same rule.

FIG. 18 shows a MAC control element including an activation indicatoraccording to an exemplary embodiment of the present invention. Here, thenumber of SSCs supportable in the system is equal to the number of bitsof the MAC control element including the activation indicator, and onlysome of the supportable SSCs are configured in the UE.

Referring to FIG. 18, bits of an activation indication MAC controlelement 1800 are sequentially mapped with all serving cell indices {1,2, 3, 4, 5, 6, 7, 8}, respectively. Indices of serving cells configuredin the UE are {3, 5, 6, 7}, and among them, indices of activated servingcells are {3, 7} and indices of deactivated serving cells are {5, 6}.Bits corresponding to the indices {1, 2, 4, 8} of the serving cells notconfigured in the UE are set to 0, and may always be set to 0. Bitscorresponding to the activated serving cell indices {3, 7} are set to 1.Bits corresponding to the deactivated serving cell indices {5, 6} areset to 0. Therefore, the activation indication MAC control element 1800is expressed by ‘01000100’.

As such, a bit corresponding to an index of a serving cell notconfigured in the UE is set to 0 as in a case in which the serving cellis deactivated. In this case, the UE ignores the bit corresponding tothe index of the serving cell not configured in the UE.

FIG. 17 and FIG. 18 show cases in which the total number of SSCssupportable in the system is equal to the total number of bits of theactivation indication MAC control element. However, if the total numberof supportable SSCs is less than the total number of bits of theactivation indication MAC control element, there is a need to determinehow to utilize the remaining bits of the activation indication MACcontrol element. This will be described below with reference to FIG. 19.

FIG. 19 shows a MAC control element including an activation indicatoraccording to an exemplary embodiment of the present invention. Here, thenumber of SSCs supportable in the system is less than the number of theMAC control element including the activation indicator.

Referring to FIG. 19, an activation indication MAC control element 1900includes at least one R field 1905. If the number of SSCs supportable inthe system is k and the number of bits of the activation indication MACcontrol element 1900 is m, then (m-k) bits, having a lengthcorresponding to the number of remaining bits in the activationindication MAC control element 1900, are reserved as the R field 1905for other usages (e.g., a usage of activating/deactivating a UL CCindependently from a DL CC). For example, if m=8 and k=4, since 4 bits(i.e., 8-4) are not used for a serving cell index, these bits areconstructed as the R field 1905.

Therefore, the activation indication MAC control element 1900 isexpressed by ‘RRRR1001’, and the remaining 4 bits (i.e., ‘1001’) otherthan the R field 1905 respectively correspond to serving cell indices ofthe SSCs supportable in the system in an order of {4, 3, 2, 1}. That is,an order according to which the serving cell indices are mapped to the 4bits is determined on the basis of the serving cell indices of the SSCssupportable in the system.

According to the number of SSCs configured in the UE, the 4 bitsindicate different information as follows. If the 4 bits are ‘abcd’, theserving cell indices {4, 3, 2, 1} sequentially correspond to the bits a,b, c, and d.

For example, it is assumed that all SSCs supportable in the system areconfigured in the UE. Since the 4 bits are ‘1001’ (a=d=1, b=c=0), thisindicates that only CCs corresponding to the serving cell indices {1, 4}are activated, and CCs corresponding to the remaining serving cellindices {2, 3} are deactivated. Herein, since a serving cell index 0indicates a PSC, it is not indicated in the activation indication MACcontrol element 1900, but it is implicitly regarded as being activated.

For another example, it is assumed that only SSCs having the servingcell indices {4, 3, 1} are configured in the UE among the SSCssupportable in the system. Since an SSC having the serving cell index{2} is not configured in the UE, among the 4 bits, a bit correspondingto the serving cell index {2} (i.e., the bit c) is set to 0, and mayalways be set to 0, such as ‘ab0d’. In this case, the UE ignores the bitc corresponding to the serving cell not configured in the UE. Further,since the 4 bits are ‘1001’ (a=d=1, b=0), CCs corresponding to theserving cell indices {1, 4} are activated, and a CC corresponding to theserving cell index {3} is deactivated.

As such, if an SSC of the serving cell index {3} corresponding to thebit c is configured in the UE, c=0 indicates deactivation of the SSC. Inthis case, the UE does not ignore the bit c, but determines whether thebit is set to 0 or 1. Otherwise, if the SSC of the serving cell index{3} corresponding to the bit c is not configured in the UE, c=0indicates non-configuration of the SSC. Since the UE can recognize thatthe bit c is 0 in any case, the UE ignores the bit c.

FIG. 20 shows a MAC control element including an activation indicatoraccording to an exemplary embodiment of the present invention. Here, aserving cell index is an index of a physical center frequency of eachserving cell (or CC), and the number of SSCs supportable in the systemis equal to the number of bits of the MAC control element including theactivation indicator.

Referring to FIG. 20, an activation indication MAC control element 2000including the activation indicator has a length of 8 bits. Each bit ofthe activation indication MAC control element 2000 corresponds to afrequency index Fi of an SSC in a one-to-one manner. For example,frequency indices 1 and 4 of the SSC respectively correspond to an8^(th) bit and a 4^(th) bit of the activation indication MAC controlelement 2000. Herein, Fi denotes an index for a center frequency i ofthe SSC (or CC). For example, F1, F2, and F3 are frequency indicesindicating 100 MHz, 120 MHz, and 140 MHz, respectively. Of course, thisis for exemplary purposes only, and a frequency size is not necessarilyincreased in an ascending order of a frequency index. The frequency sizemay be decreased or may be defined randomly or without any order orrelation to the other frequency sizes.

If a PSC is always activated between the eNB and the UE, the activationindicator does not have to additionally indicate a frequency index forthe PSC. Therefore, the activation indication MAC control element 2000can indicate activation/deactivation regarding up to 8 SSCs. If thefrequency index of the PSC is F0, frequency indices of the remainingSSCs can be given to F1 to F8. Therefore, as shown in FIG. 20, thefrequency indices F1 to F8 are sequentially mapped respectively from an8^(th) bit to a 1^(st) bit of the activation indication MAC controlelement 2000.

Frequency indices of SSCs supportable in the system are {F1, F2, F3, F4,F5, F6, F7, F8}, and all of the SSCs are configured in the UE. Amongthem, frequency indices of activated SSCs are {F1, F4, F7, F8}.Therefore, the activation indication MAC control element 2000 isexpressed by ‘11001001’.

However, this is for exemplary purposes only, and thus the frequencyindices F1 to F8 can be sequentially mapped respectively from the 1^(st)bit to the 8^(th) bit of the activation indication MAC control element2000, or may be randomly mapped.

FIG. 21 shows a MAC control element including an activation indicatoraccording to an exemplary embodiment of the present invention. Here, aserving cell index is an index of a physical center frequency of eachserving cell, and the number of SSCs supportable in the system is lessthan the number of bits of the MAC control element including theactivation indicator.

Referring to FIG. 21, an activation indication MAC control element 2100includes at least one R field 2105. If the number of SSCs configured inthe UE is k and the number of bits of the activation indication MACcontrol element 2100 is m, then (m-k) bits, having a lengthcorresponding to the number of remaining bits in the activationindication MAC control element 2100, are reserved for other usages(e.g., a usage of activating/deactivating a UL CC independently from aDL CC). For example, if the number of bits of the activation indicationMAC control element 2100 is 8 and the maximum number of serving cellssupportable in the system is 4, since 4 bits (i.e., 8-4) are not usedfor a frequency index of an SSC, these bits are constructed as the Rfield 2105.

Therefore, the activation indication MAC control element 2100 isexpressed by ‘RRR1001’, and the remaining last 4 bits other than the Rfield 2105 respectively correspond to frequency indices {F4, F3, F2, F1}of the SSC supportable in the system. Since the last 4 bits are ‘1001’,this indicates that only CCs corresponding to the frequency indices {F4,F1} are activated, and CCs corresponding to the remaining frequencyindices {F3, F2} are deactivated. Herein, since the frequency index F0indicates a PSC, even through it is not indicated by the activationindicator, the PSC is implicitly regarded as being activated. However,the index of the PSC is not necessarily F0, and thus can be given toanother index. In this case, the index of the PSC is excluded from theactivation indicator.

Meanwhile, if the number of SSCs configured in the UE is less than themaximum number of CCs supportable in the system, a bit corresponding toa frequency index of a non-configured SSC in the activation indicationMAC control element 2100 is set to 0. In this case, the UE ignores thebit corresponding to the SSC not configured in the UE.

Although it is described herein that the number of R fields 2105 is 4,this for exemplary purposes only, and thus the R field 2105 may notexist or the number of R fields 2105 may be greater (or fewer) than orequal to 4.

FIG. 22 shows a MAC control element including an activation indicatoraccording to an exemplary embodiment of the present invention. Here, thenumber of SSCs configured in the UE is less than the number of SSCssupportable in the system. Herein, whether the number of supportableSSCs is equal to or different from the number of bits of an activationindication MAC control element is not a matter of concern in particular.However, for convenience of explanation, it is assumed that the numberof supportable SSCs is less than the total number of bits of theactivation indication MAC control element, and the activation indicationMAC control element includes at least one R field.

Referring to FIG. 22, an activation indication MAC control element 2200includes 4 R fields 2205 and 4 bits. The number of SSCs supportable inthe system is 4, and serving cell indices of the SSCs are {4, 3, 2, 1}.Among the 4 SSCs, x cells are configured in the UE (where x≦4). In thiscase, an order of mapping the serving cell indices to the 4 bits isdetermined on the basis of serving cell indices for the x SSCs and isnot determined on the basis of the serving cell indices of the 4 SSCssupportable in the system.

If serving cell indices of 3 SSCs configured in the UE are {4, 3, 1},any 3 bits out of the 4 bits indicate activation/deactivation of the 3SSCs, and the remaining 1 bit is set to 0, and may always be set to 0.For example, if the 4 bits are ‘abcd’, the bit a is 0, and the remainingbits b, c, and d correspond to the serving cell indices of the 3 SSCs.In the example of FIG. 22, the serving cell indices {4, 3, 1}sequentially correspond to the bits b, c, and d, respectively. Sincebcd=101, the activation indication MAC control element 2200 indicatesactivation of CCs corresponding to the serving cell indices {4, 1} andindicates deactivation of a CC corresponding to the serving cell index{3}. Of course, this is for exemplary purposes only, and thus any one ofthe bits b, c, and d can be set to 0. For example, if c=0, this exampleis the same as the example of FIG. 19.

Although it is described herein that the number of R fields 2205 is 4,this is for exemplary purposes only, and thus the R field 2205 may notexist or the number of R fields 2205 may be greater than (or fewer than)or equal to 4.

FIG. 23 shows a MAC control element including an activation indicatoraccording to an exemplary embodiment of the present invention. Here, thenumber of SSCs configured in the UE is less than the number of SSCssupportable in the system, and a serving cell index is an index of aphysical center frequency of each serving cell.

Referring to FIG. 23, an activation indication MAC control element 2300includes 4 R fields 2305 and 4 bits. The number of SSCs supportable inthe system is 4, and frequency indices of the SSCs are {F4, F3, F2, F1}.Among the 4 SSCs, x cells are configured in the UE (where x≦4). In thiscase, an order of mapping the serving cell index to the 4 bits isdetermined on the basis of serving cell indices for the x SSCs and isnot determined on the basis of the serving cell indices of the 4 SSCssupportable in the system.

If frequency indices of 3 SSCs configured in the UE are {F4, F3, F1},any 3 bits out of the 4 bits indicate activation/deactivation of the 3SSCs, and the remaining 1 bit is set to 0, and may always be set to 0.For example, if the 4 bits are ‘abcd’, the bit a is 0, and the remainingbits b, c, and d correspond to the serving cell indices of the 3 SSCs.In the example of FIG. 23, the frequency indices {F4, F3, F1}sequentially correspond to the bits b, c, and d, respectively. Sincebcd=101, the activation indication MAC control element 2300 indicatesactivation of CCs corresponding to the frequency indices {F4, F1} andindicates deactivation of a CC corresponding to the frequency index{F3}. Of course, this is for exemplary purposes only, and thus any oneof the bits b, c, and d can be set to 0. For example, if c=0, thisexample is the same as the example of FIG. 21.

Although it is described herein that the number of R fields 2305 is 4,this is for exemplary purposes only, and thus the R field 2305 may notexist or the number of R fields 2205 may be greater (or fewer) than orequal to 4.

FIG. 24 shows a MAC control element including an activation indicatoraccording to an exemplary embodiment of the present invention. Here, theeNB reports to the UE that respective bits of an activation indicationMAC control element correspond to serving cell indices arranged in aspecific order by using RRC signaling, and the number of SSCs configuredin the UE is equal to the number of SSCs supportable in the system.Herein, whether the number of supportable SSCs is equal to or differentfrom the number of bits of the activation indication MAC control elementis not a matter of concern in particular. However, for convenience ofexplanation, it is assumed that the number of supportable SSCs is lessthan the total number of bits of the activation indication MAC controlelement, and the activation indication MAC control element includes atleast one R field.

Referring to FIG. 24, an activation indication MAC control element 2400includes 4 R fields 2405 and 4 bits. The number of SSCs supportable inthe system is 4, and serving cell indices of the SSCs are respectively{4, 3, 2, 1}, and all of them are configured in the UE.

In FIG. 17 to FIG. 23, it is assumed that a correspondence relationbetween a bit and a serving cell index is previously known between theeNB and the UE without additional signaling. Unlike this, in FIG. 24,index mapping information for indicating a mapping relation between abit position and a serving cell index of an SSC supportable in thesystem is transmitted by the eNB to the UE. The UE receives the indexmapping information, and determines the mapping relation between the bitposition and the serving cell index by using the index mappinginformation. Thereafter, if the eNB confirms that the UE receives theindex mapping information, the eNB transmits the activation indicator tothe UE. The index mapping information may be any one of a MAC message,an RRC message, and a physical layer message.

For example, if the 4 bits are ‘abcd’, the bits a, b, c, and drespectively correspond to 4 serving cell indices. According to theindex mapping information of FIG. 24, the serving cell index {1} ismapped to the bit a, the serving cell index {2} is mapped to the bit b,the serving cell index {4} is mapped to the bit c, and the serving cellindex {3} is mapped to the bit d.

The UE determines a serving cell index to be mapped to each bit positionon the basis of the index mapping information, and then determinesactivation/deactivation of each SSC on the basis of the activationindication MAC control element 2400 including the activation indicator.The remaining 4 bits other than the R field 2405 in the activationindication MAC control element 2400 are abcd=1100. Therefore, theactivation indication MAC control element 2400 indicates activation ofCCs corresponding to the serving cell indices {1, 2} and indicatesdeactivation of CCs corresponding to the serving cell indices {3, 4}.Accordingly, the UE does not receive the CCs corresponding to theserving cell indices {3, 4} but receives the CCs corresponding to theserving cell indices {1, 2}.

FIG. 25 shows a MAC control element including an activation indicatoraccording to an exemplary embodiment of the present invention. Here, theeNB reports to the UE that respective bits of an activation indicationMAC control element correspond to serving cell indices arranged in aspecific order by using RRC signaling, and the number of SSCs configuredin the UE is less than the number of SSCs supportable in the system.Herein, whether the number of supportable SSCs is equal to or differentfrom the number of bits of the activation indication MAC control elementis not a matter of concern in particular. However, for convenience ofexplanation, it is assumed that the number of supportable SSCs is lessthan the total number of bits of the activation indication MAC controlelement, and the activation indication MAC control element includes atleast one R field.

Referring to FIG. 25, an activation indication MAC control element 2500includes 4 R fields 2505 and 4 bits. The number of SSCs supportable inthe system is 4, and serving cell indices of the SSCs are respectively{4, 3, 2, 1}. Among them, SSCs corresponding to {2, 4, 3} are configuredin the UE.

The eNB first transmits index mapping information to the UE. If the 4bits are ‘abcd’, mapping between SSCs supportable in the system can beachieved as follows. That is, the serving cell index {1} is mapped tothe bit a, the serving cell index {2} is mapped to the bit b, theserving cell index {4} is mapped to the bit c, and the serving cellindex {3} is mapped to the bit d. That is, a mapping relation of abcd

{1, 2, 4, 3} is satisfied.

However, since the SSC having the serving cell index {1} is notconfigured in the UE, the bit a is set to 0. Since the remaining bitsare bcd=100, the activation indication MAC control element 2500indicates activation of the SSC having the serving cell index {2} andindicates deactivation of the SSCs having the serving cell indices {3,4}.

2. Structure of Activation Indicator for Case 2

Unlike in Case 1, an activation indicator for Case 2 not only includesan SSC but also explicitly includes indication ofactivation/deactivation of a PSC. Therefore, at least one bit of anactivation indication MAC control element corresponds to a serving cellindex, and in this sense, the structure of the activation indicator forCase 2 is different from that of Case 1. Hereinafter, a serving cellincludes both the PSC cell and the SSC. In addition, a serving cellindex refers to both a serving cell index of the PSC and a serving cellindex of the SSC. A frequency index and the serving cell index of thePSC may be determined differently for each UE and/or for each eNB.However, except for a special case, for consistency of overallexplanations herein, the serving cell index of the PSC is 0 and thefrequency index of the PSC is F0.

FIG. 26 shows a MAC control element including an activation indicatoraccording to an exemplary embodiment of the present invention. Here, thenumber of serving cells supportable in the system is equal to the numberof bits of an activation indication MAC control element, the number ofall supportable serving cells is 8, and 8 serving cells are configuredin the UE.

Referring to FIG. 26, an activation indication MAC control element 2600has a length of 8 bits. Bit positions of the activation indication MACcontrol element 2600 respectively correspond to serving cell indices ina one-to-one manner. Herein, the serving cell index comprises a servingcell index of an SSC or a PSC. The example of FIG. 26 is different fromthe example of FIG. 17 in that the serving cell index explicitlycorresponds to each bit of the activation indication MAC control element2600. Therefore, the serving cell indices are given to 0, 1, 2, 3, . . ., 7.

Since the activation indication MAC control element 2600 has a length of8 bits, the activation indicator can indicate one PSC index and 7 SSCindices. That is, the activation indicator can cover up to 8 CCs capableof indicating activation/deactivation.

If all supportable serving cells are configured in the UE, then 8serving cells are configured in the UE. The activation indication MACcontrol element 2600 is ‘11001001’, and bits from the left respectivelycorrespond to serving cell indices {7, 6, 5, 4, 3, 2, 1, 0}.

Herein, the index of one PSC is set to a fixed value, i.e., 0. Further,the PSC may always be set to the activation state. Accordingly, theactivation indicator for the PSC may always be set to 1.

As described above, since the PSC is in the activation state, and mayalways be in the activation state, an exemplary embodiment of thepresent invention may further include a case in which indicationinformation (i.e., an indicator) for indicating the activation state ofthe PSC is not included in the activation indication MAC control element2600. That is, an exemplary embodiment of the present invention furtherincludes the activation indication MAC control element 2600 configuredwith a reserved (R) bit in the absence of the activation indicator forthe PSC. In this case, the UE may not analyze a value of the R bit, thatis, since the UE is aware that the index of the PSC is 0, the PSC mayremain in the activation state without additional analysis.

Therefore, the activation indicator indicates activation of CCscorresponding to the serving cell indices {0, 3, 6, 7}, and indicatesdeactivation of CCs corresponding to the serving cell indices {1, 2, 4,5}. An order of a serving cell index corresponding to a position of eachbit of the activation indication MAC control element 2600 is forexemplary purposes only, and the serving cell index does not have to bearranged in the order of FIG. 26 and thus may be arranged in anotherorder. However, if there is no additional signaling, the UE and the eNBhave to know an order according to which each serving cell indexcorresponds to each bit of the activation indication MAC control element2600.

FIG. 27 shows a MAC control element including an activation indicatoraccording to an exemplary embodiment of the present invention. Here, thenumber of serving cells supportable in the system is equal to the numberof bits of the MAC control element including the activation indicator,and only some of supportable serving cells are configured in the UE.

Referring to FIG. 27, bits of an activation indication MAC controlelement 2700 are sequentially mapped with all serving cell indices {0,1, 2, 3, 4, 5, 6, 7}, respectively. First, serving cells not configuredin the UE have serving cell indices {1, 2, 4}. Therefore, bitscorresponding to {1, 2, 4} are set to 0, and may always be set to 0.Serving cells configured in the UE have serving cell indices {0, 3, 5,6, 7}. Since the activation indication MAC control element 2700 is‘0100001’, this indicates activation of serving cells having the servingcell indices {0, 6} and indicates deactivation of serving cells havingthe serving cell indices {3, 5, 7}. The UE ignores a bit correspondingto an index of a serving cell not configured in the UE.

In addition, the UE may confirm the activation indication MAC controlelement 2600 configured with the R bit in correspondence with the PSC,and thus the PSC may remain in the activation state without additionalanalysis on the R bit.

FIG. 26 and FIG. 27 show examples in which the total number of servingcells supportable in the system is equal to the total number ofactivation indication MAC control elements. However, if the total numberof supportable serving cells is less than the total number of bits ofthe activation indication MAC control element, there is a need todetermine how to utilize the remaining bits of the activation indicationMAC control element. This will be described below with reference to FIG.28.

FIG. 28 shows a MAC control element including an activation indicatoraccording to an exemplary embodiment of the present invention. This is acase in which the number of serving cells supportable in the system isless than the number of bits of the MAC control element including theactivation indicator.

Referring to FIG. 28, an activation indication MAC control element 2800includes at least one R field 2805. If the number of serving cellssupportable in the system is k and the number of bits of the activationindication MAC control element 2800 is m, then (m-K) bits, having alength corresponding to the number of remaining bits in the activationindication MAC control element 2800, are reserved as the R field 2805for other usages (e.g., a usage of activating/deactivating a UL CCindependently from a DL CC). For example, if m=8 and k=5, then, since 3bits (i.e., 8-5) are not used for a serving cell index, these bits areconstructed as the R field 2805.

Therefore, the activation indication MAC control element 2800 isexpressed by ‘RRR11001’, and the remaining 5 bits (i.e., ‘11001’) otherthan the R field 2805 respectively correspond to serving cell indices ofthe serving cells supportable in the system in an order of {4, 3, 2, 1,0}. That is, an order according to which the serving cell index ismapped to the 5 bits is determined based on a serving cell index of theserving cells supportable in the system.

According to the number of serving cells configured in the UE, the 5bits indicate different information as follows. If the 5 bits are‘abcde’, the serving cell indices {4, 3, 2, 1, 0} sequentiallycorrespond to the bits a, b, c, d, and e.

For example, it is assumed that all serving cells supportable in thesystem are configured in the UE. Since the 5 bits are ‘11001’ (a=b=e=1,c=d=0), this indicates that only CCs corresponding to the serving cellindices {0, 3, 4} are activated, and CCs corresponding to the remainingserving cell indices {1, 2} are deactivated. Herein, a serving cellindex 0 is a serving cell index of a PSC.

For another example, it is assumed that only serving cells having theserving cell indices {4, 3, 1, 0} are configured in the UE among theserving cells supportable in the system. That is, a serving cell havingthe serving cell index {2} is not configured in the UE. In this case,among the 5 bits, a bit corresponding to the serving cell index {2},i.e., the bit c, is set to 0, and may always be set to 0, such as‘ab0de’. In this case, the UE ignores the bit c corresponding to theserving cell not configured in the UE. Further, since the 5 bits are‘11001’(a=b=e=1, d=0), this indicates that the CCs corresponding to theserving cell indices {0, 3, 4} are activated, and the CC correspondingto the serving cell index {1} is deactivated.

FIG. 29 shows a MAC control element including an activation indicatoraccording to an exemplary embodiment of the present invention. Here, aserving cell index is an index of a physical center frequency of eachserving cell (or CC), and the number of serving cells supportable in thesystem is equal to the number of bits of the MAC control elementincluding the activation indicator.

Referring to FIG. 29, an activation indication MAC control element 2900including the activation indicator has a length of 8 bits. Each bit ofthe activation indication MAC control element 2900 corresponds to afrequency index Fi of a serving cell in a one-to-one manner. Forexample, frequency indices 1 and 4 of the serving cell respectivelycorrespond to an 8^(th) bit and a 4^(th) bit of the activationindication MAC control element 2900. Herein, Fi denotes an index for acenter frequency i of the serving cell (or CC). For example, F0, F1, F2,and F3 are frequency indices indicating 90 MHz, 100 MHz, 120 MHz, and140 MHz, respectively. Of course, this is for exemplary purposes only,and a frequency size is not necessarily increased in an ascending orderof a frequency index. The frequency size may be decreased or may bedefined randomly or without any order or relation to the other frequencysizes.

The activation indication MAC control element 2900 can indicateactivation/deactivation regarding up to 8 serving cells. If thefrequency index of the PSC is F0, frequency indices of the remainingSSCs can be given to F1 to F7. Therefore, as shown in FIG. 29, thefrequency indices F1 to F7 are sequentially mapped respectively from an8^(th) bit to a 1^(st) bit of the activation indication MAC controlelement 2900.

Frequency indices of serving cells supportable in the system are {F0,F1, F2, F3, F4, F5, F6, F7}, and all of the serving cells are configuredin the UE. Among them, frequency indices of activated serving cells are{F0, F3, F6, F7}. Therefore, the activation indication MAC controlelement 2900 is expressed by ‘11001001’.

However, this is for exemplary purposes only, and thus the frequencyindices F0 to F7 can be sequentially mapped respectively from the 1^(st)bit to the 8^(th) bit of the activation indication MAC control element2900, or may be randomly mapped.

FIG. 30 shows a MAC control element including an activation indicatoraccording to an exemplary embodiment of the present invention. Here, aserving cell index is an index of a physical center frequency of eachserving cell, and the number of serving cells supportable in the systemis less than the number of bits of the MAC control element constructingthe activation indicator.

Referring to FIG. 30, an activation indication MAC control element 3000includes at least one R field 3005. If the number of serving cellsconfigured in the UE is k and the number of bits of the activationindication MAC control element 3000 is m, then (m-k) bits, having alength corresponding to the number of remaining bits in the activationindication MAC control element 3000, are reserved for other usages(e.g., a usage of activating/deactivating a UL CC independently from aDL CC). For example, if the number of bits of the activation indicationMAC control element 3000 is 8 and the maximum number of serving cellssupportable in the system is 5, then, since 3 bits (i.e., 8-5) are notused for a frequency index of a serving cell, these bits are constructedas the R field 3005.

Therefore, the activation indication MAC control element 3000 isexpressed by ‘RRR11001’, and the remaining last 5 bits other than the Rfield 3005 respectively correspond to frequency indices {F4, F3, F2, F1,F0} of the serving cell supportable in the system. Since the last 5 bitsare ‘11001’, this indicates that only CCs corresponding to the frequencyindices {F4, F3, F0} are activated, and CCs corresponding to theremaining frequency indices {F2, F1} are deactivated.

Meanwhile, if the number of serving cells configured in the UE is lessthan the maximum number of CCs supportable in the system, a bitcorresponding to a non-configured serving cell in the activationindication MAC control element 3000 is set to 0. In this case, the UEignores the bit corresponding to the serving cell not configured in theUE.

Although it is described herein that the number of R fields 3005 is 3,this for exemplary purposes only, and thus the R field 3005 may notexist or the number of R fields 3005 may be greater (or fewer) than orequal to 3.

FIG. 31 shows a MAC control element including an activation indicatoraccording to an exemplary embodiment of the present invention. Here, thenumber of serving cells configured in the UE is less than the number ofserving cells supportable in the system. Herein, whether the number ofsupportable serving cells is equal to or different from the number ofbits of an activation indication MAC control element is not a matter ofconcern in particular. However, for convenience of explanation, it isassumed that the number of supportable serving cells is less than thetotal number of bits of the activation indication MAC control element,and the activation indication MAC control element includes at least oneR field.

Referring to FIG. 31, an activation indication MAC control element 3100includes 3 R fields 3105 and 5 bits. The number of serving cellssupportable in the system is 5, and serving cell indices of the servingcells are {4, 3, 2, 1, 0}. Among the 5 serving cells, x cells areconfigured in the UE (where x≦5). In this case, an order of mapping theserving cell index to the 5 bits is determined on the basis of servingcell indices for the x serving cells and is not determined on the basisof the serving cell indices of the 5 serving cells supportable in thesystem.

If serving cell indices of 3 serving cells configured in the UE are 13,1, 01, any 3 bits out of the 5 bits indicate activation/deactivation ofthe 3 serving cells, and the remaining 2 bits are set to 0, and mayalways be set to 0. For example, if the 5 bits are ‘abcde’, the bits aand b are 0, and the remaining bits c, d, and e correspond to theserving cell indices of the 3 serving cells. In the example of FIG. 31,the serving cell indices {3, 1, 0} sequentially correspond to the bitsc, d, and e, respectively. Since cde=101, the activation indication MACcontrol element 3100 indicates activation of CCs corresponding to theserving cell indices {3, 0} and indicates deactivation of a CCcorresponding to the serving cell index {1}. Of course, this is forexemplary purposes only, and thus any one of the bits a, b, c, d, and ecan be set to 0, or may always be set to 0.

Although it is described herein that the number of R fields 3105 is 3,this is for exemplary purposes only, and thus the R field 3105 may notexist or the number of R fields 3105 may be greater (or fewer) than orequal to 3.

FIG. 32 shows a MAC control element including an activation indicatoraccording to an exemplary embodiment of the present invention. This is acase in which the number of serving cells configured in the UE is lessthan the number of serving cells supportable in the system, and aserving cell index is an index of a physical center frequency of eachserving cell.

Referring to FIG. 32, an activation indication MAC control element 3200includes 3 R fields 3205 and 5 bits. The number of serving cellssupportable in the system is 5, and frequency indices of the servingcells are {F4, F3, F2, F1, F0}. Among the 5 serving cells, x cells areconfigured in the UE (where x≦5). In this case, an order of mapping theserving cell index to the 5 bits is determined on the basis of servingcell indices for the x serving cells and is not determined on the basisof the serving cell indices of the 5 serving cells supportable in thesystem.

If frequency indices of 3 serving cells configured in the UE are {F3,F1, F0}, any 3 bits out of the 5 bits indicate activation/deactivationof the 3 serving cells, and the remaining 2 bits are set to 0, and mayalways be set to 0. For example, if the 5 bits are ‘abcde’, the bits aand b are 0, and the remaining bits c, d, and e correspond to theserving cell indices of the 3 serving cells. In the example of FIG. 32,the frequency indices {F3, F1, F0} sequentially correspond to the bitsc, d, and e, respectively. Since cde=101, the activation indication MACcontrol element 3200 indicates activation of CCs corresponding to thefrequency indices {F3, F0} and indicates deactivation of a CCcorresponding to the frequency index {F1}. Of course, this is forexemplary purposes only, and thus any one of the bits a, b, c, d, and ecan be set to 0, or always set to 0.

Although it is described herein that the number of R fields 3205 is 3,this is for exemplary purposes only, and thus the R field 3205 may notexist or the number of R fields 3205 may be greater (or fewer) than orequal to 3.

FIG. 33 shows a MAC control element including an activation indicatoraccording to an exemplary embodiment of the present invention. Here, theeNB reports to the UE that respective bits of an activation indicationMAC control element correspond to serving cell indices arranged in aspecific order by using RRC signaling, and the number of serving cellsconfigured in the UE is equal to the number of serving cells supportablein the system. Herein, whether the number of supportable serving cellsis equal to or different from the number of bits of the activationindication MAC control element is not a matter of concern in particular.However, for convenience of explanation, it is assumed that the numberof supportable serving cells is less than the total number of bits ofthe activation indication MAC control element, and the activationindication MAC control element includes at least one R field.

Referring to FIG. 33, an activation indication MAC control element 3300includes 3 R fields 3305 and 5 bits. The number of serving cellssupportable in the system is 5, and serving cell indices of the servingcells are respectively {0, 1, 2, 3, 4}, and all of them are configuredin the UE.

In FIG. 26 to FIG. 32, it is assumed that a correspondence relationbetween a bit and a serving cell index is previously known between theeNB and the UE without additional signaling. Unlike this, in FIG. 33,the UE maps a serving cell index and each bit position by using indexmapping information for indicating a mapping relation between a bitposition and a serving cell index of a serving cell supportable in thesystem.

For example, if the 5 bits are ‘abcde’, the bits a, b, c, d, and erespectively correspond to 5 serving cell indices. According to theindex mapping information of FIG. 33, the serving cell index {1} ismapped to the bit a, the serving cell index {2} is mapped to the bit b,the serving cell index {0} is mapped to the bit c, the serving cellindex {4} is mapped to the bit d, and the serving cell index {3} ismapped to the bit e.

The UE determines a serving cell index to be mapped to each bit positionon the basis of the index mapping information, and then determinesactivation/deactivation of each serving cell on the basis of theactivation indication MAC control element 3300 including the activationindicator. The remaining 5 bits other than the R field 3305 in theactivation indication MAC control element 3300 are abcde=10101.Therefore, the activation indication MAC control element 3300 indicatesactivation of CCs corresponding to the serving cell indices {1, 0, 3}and indicates deactivation of CCs corresponding to the serving cellindices {2, 4}. Accordingly, the UE does not receive the CCscorresponding to the serving cell indices {2, 4} but receives the CCscorresponding to the serving cell indices {1, 0, 3}.

FIG. 34 shows a MAC control element including an activation indicatoraccording to an exemplary embodiment of the present invention. Here, theeNB reports to the UE that respective bits of an activation indicationMAC control element correspond to serving cell indices arranged in aspecific order by using RRC signaling, and the number of serving cellsconfigured in the UE is less than the number of serving cellssupportable in the system. Herein, whether the number of supportableserving cells is equal to or different from the number of bits of theactivation indication MAC control element is not a matter of concern inparticular. However, for convenience of explanation, it is assumed thatthe number of supportable serving cells is less than the total number ofbits of the activation indication MAC control element, and theactivation indication MAC control element includes at least one R field.

Referring to FIG. 34, an activation indication MAC control element 3400includes 3 R fields 3405 and 5 bits. The number of serving cellssupportable in the system is 5, and serving cell indices of the servingcells are respectively {0, 1, 2, 3, 4}. Among them, serving cellscorresponding to {0, 3, 4} are configured in the UE.

The eNB first transmits index mapping information to the UE. If the 5bits are ‘abcde’, mapping between serving cells supportable in thesystem can be achieved as follows. That is, the serving cell index {1}is mapped to the bit a, the serving cell index {2} is mapped to the bitb, the serving cell index {0} is mapped to the bit c, the serving cellindex {4} is mapped to the bit d, and the serving cell index {3} ismapped to the bit e. That is, a mapping relation of abcde

{1, 2, 0, 4, 3} is satisfied.

However, since the serving cells corresponding to the serving cellindices {1, 2} are not configured in the UE, the bits a and b are set to0, and may always be set to 0. Since the remaining bits are cde=101, theactivation indication MAC control element 3400 indicates activation ofthe serving cells corresponding to the serving cell indices {0, 3} andindicates deactivation of the serving cell corresponding to the servingcell index {4}.

FIG. 35 is a flowchart showing a method for transmitting an activationindicator according to an exemplary embodiment of the present invention.Referring to FIG. 35, an eNB transmits index mapping information to a UE(operation S3500). The index mapping information is information forindicating a mapping relation between a bit position and a serving cellindex of an SSC supportable in the system. The UE may allow each bit ofan activation indication MAC control element to be received afterwardsto correspond to a serving cell index on the basis of the index mappinginformation. If the index mapping information is successfully received,and each bit of the activation indication MAC control element is allowedto correspond to the serving cell index on the basis of the indexmapping information, the UE transmits mapping confirmation informationto the eNB (operation S3505).

The index mapping information and the mapping confirmation informationmay be any one of a MAC message, an RRC message, and a physical layermessage.

The eNB transmits the activation indicator to the UE (operation S3510).The activation indicator may have the structure described with referenceto FIG. 16 to FIG. 34, and may also have other similar structures inaddition thereto.

Although not shown in FIG. 35, by using the activation indicator, the UEmay activate (or receive) a specific CC regarding a specific servingcell index or may deactivate (or not receive) the specific CC.

According to exemplary embodiments of the present invention, a controlchannel or data channel regarding a component carrier is selectivelyreceived depending on whether the component carrier is activated while adeactivated component carrier is not received. Therefore, decodingoverhead of a user equipment may be decreased, and power consumption maybe decreased.

In addition, a transport protocol regarding activation/deactivation ofthe component carrier is clearly specified between the user equipmentand a base station, and an amount of control information required forthis process is regulated. Therefore, a radio resource can beeffectively used.

It will be apparent to those skilled in the art that variousmodifications and variation can be made in the present invention withoutdeparting from the spirit or scope of the invention. Thus, it isintended that the present invention cover the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

What is claimed is:
 1. A method for controlling cell activation by abase station (BS), comprising: transmitting, to a user equipment (UE), aserving cell configuration comprising one or more indices to configureone or more serving cells through radio resource control (RRC);determining activation or deactivation of each serving cell which isconfigured in the UE; setting the determined activation or deactivationto a 1-bit indicator; and transmitting, to the UE, a medium accesscontrol signal comprising indicators for the one or more serving cellsconfigured in the UE in a bit-stream consisting of eight bits, whereinthe one or more serving cells is configurable by the UE based on theserving cell configuration, the one or more serving cells being a subsetof serving cells configurable by the BS, wherein the activationinstructs the UE to monitor reception of at least one of a controlchannel and the deactivation instructs the UE to stop monitoringreception of at least one of the control channel, and wherein theactivation is set to 1 and the deactivation is set to
 0. 2. The methodof claim 1, wherein the serving cell configuration indicates a servingcell through which system information of another serving cell configuredin the UE is received.
 3. The method of claim 1, wherein the bit-streamcomprises at least one reserved bit not available for the indicators forthe one or more serving cells configured in the UE, and whereinremaining bits of the bit-stream correspond to the indicators for theserving cell configured in the UE.
 4. The method of claim 1, wherein thebit-stream has a format of a bitmap, and respective indices of the oneor more serving cells are mapped in a one-to-one manner to bits locatedin specific positions in the bitmap.
 5. The method of claim 4, whereineach of component carriers (CCs) is a CC configured in the UE, andwherein the CC is a serving cell to transmit and receive informationbetween the BS and the UE, and the serving cell has a linkage between anuplink CC and a downlink CC.
 6. The method of claim 1, wherein, in thedetermining of activation or deactivation, at least one of a powercharacteristic of the UE, a radio frequency (RF) device characteristic,a baseband transmission/reception scheme, a number of antennas, a linkcapacity, which comprises receive power or interference power or noisepower or a sum of two power levels or a ratio of the receive power tothe interference power or a ratio of the receive power to theinterference power and the noise power in the UE, and an availableserving cell is determined by considering at least one of an independentresource usage rate corresponding to each of the control channel and adata channel of the BS, battery power consumption considering the numberof serving cells of the UE, a diversity gain, and system reliabilityconsidering the number of serving cells of the BS.
 7. A method forcontrolling cell activation by a user equipment (UE), comprising:receiving a serving cell configuration comprising one or more indices toconfigure one or more serving cells through radio resource control(RRC); receiving a medium access control (MAC) signal comprisingindicators for the one or more serving cells configured in the UE in abit-stream consisting of eight bits; and monitoring the one or moreserving cells if a corresponding serving cell indicator is 1 or stoppingmonitoring the serving cell if the corresponding serving cell indicatoris 0, wherein the UE configures the one or more serving cells based onthe serving cell configuration, the one or more serving cells being asubset of serving cells configurable by a base station (BS).
 8. Themethod of claim 7, wherein the serving cell configuration indicates aserving cell through which system information of another serving cellconfigured in the UE is received.
 9. The method of claim 7, wherein theUE receives at least one control channel by monitoring the one or moreserving cells or the UE stops receiving the at least one control channelby stopping monitoring of the one or more serving cell.
 10. The methodof claim 7, wherein the bit-stream comprises at least one reserved bitnot available for the indicators for the one or more serving cellsconfigured in the UE, and wherein remaining bits of the bit-streamcorrespond to the indicators for the one or more serving cellsconfigured in the UE.
 11. The method of claim 7, wherein the bit-streamhas a format of a bitmap, and respective indices of the one or moreserving cells are mapped in a one-to-one manner to bits located inspecific positions in the bitmap.
 12. The method of claim 11, whereineach of component carriers (CCs) is a CC configured in the UE, andwherein the CC is a serving cell to transmit and receive informationbetween the BS and the UE, and the serving cell has a linkage between anuplink CC and a downlink CC.
 13. A user equipment (UE) to control cellactivation, comprising: a reception processor to receive a serving cellconfiguration comprising one or more indices to configure one or moreserving cells through radio resource control (RRC), and to receive amedium access control (MAC) signal comprising indicators for the one ormore serving cells configured in the UE in a bit-stream consisting ofeight bits; and a monitoring processor to monitor the one or moreserving cells if a corresponding serving cell indicator is 1 or to stopmonitoring the serving cell if the corresponding serving cell indicatoris 0, wherein the UE configures the one or more serving cells based onthe serving cell configuration, the one or more serving cells being asubset of serving cells configurable by a base station (BS).
 14. The UEof claim 13, wherein the serving cell configuration indicates a servingcell through which system information of another serving cell configuredin the UE is received.
 15. The UE of claim 13, wherein the UE receivesat least one control channel by monitoring the one or more serving cellsor the UE stops receiving the at least one control channel by stoppingmonitoring of the one or more serving cells.
 16. The UE of claim 13,wherein the bit-stream comprises at least one reserved bit not availablefor the indicators for the one or more serving cells configured in theUE, and wherein remaining bits of the bit-stream correspond to theindicators for the one or more serving cells configured in the UE. 17.The UE of claim 13, wherein the bit-stream has a format of a bitmap, andrespective indices of the one or more serving cells are mapped in aone-to-one manner to bits located in specific positions in the bitmap.18. The UE of claim 17, wherein each of component carriers (CCs) is a CCconfigured in the UE, and wherein the CC is a serving cell to transmitand receive information between the BS and the UE, and the serving cellhas a linkage between an uplink CC and a downlink CC.